Method for transmitting data in a blood glucose system and corresponding blood glucose system

ES 2 336 360 T3

DESCRIPTION

Method for transmitting data in a blood glucose system and corresponding blood glucose system.

The present invention relates to a method for wireless transmission of data between components of a blood glucose system including a master controller and a slave device comprising an insulin dispensing means, and to the corresponding blood glucose system .

Diabetes mellitus is a chronic metabolic disorder caused by the inability of the pancreas to produce sufficient amounts of the hormone insulin so that the metabolism is unable to provide adequate absorption of sugar and starch. This failure leads to hyperglycemia, that is, the presence of an excessive amount of glucose within the blood plasma. Persistent hyperglycemia causes a variety of serious symptoms and long-term lifelong treatment complications such as dehydration, ketoacidosis, diabetic coma, cardiovascular disease, chronic kidney failure, retinal damage, and nerve damage with the risk of limb amputation . As healing is not yet possible, permanent therapy is necessary to provide constant glycemic control to allow the blood glucose level to be maintained within normal limits. Such glycemic control is achieved by regularly supplying external insulin to the patient's body to thereby reduce elevated blood glucose levels.

External insulin was commonly administered by typically one or two daily injections of a mixture of intermediate and rapid acting insulin via a hypodermic syringe. Although this treatment does not require frequent estimation of glucose in the blood, the degree of glycemic control that can be achieved in this way has been found to be suboptimal because the delivery is different from the physiological insulin production, of whereby insulin enters the bloodstream at a lower rate and over a longer period of time. Improved glycemic control can be achieved by so-called intensive insulin therapy which is based on multiple daily injections, including one or two injections per day of long-acting insulin to provide basal insulin and additional injections of rapid-acting insulin before each meal in an amount proportional to the amount of food. Although traditional syringes have been replaced, at least partially by insulin pens, frequent injections are nevertheless very inconvenient for the patient.

Substantial improvements in diabetes therapy have been achieved by the development of blood glucose systems that relieve the patient from the daily use of insulin syringes and pens. Such blood glucose systems usually comprise a battery powered insulin pump and a separate battery powered control unit. The insulin pump allows the delivery of insulin in a more physiological way and can be controlled to follow standardized protocols or individually modified to provide the patient with better glycemic control throughout the day. It may be constructed as an implantable device for subcutaneous arrangement or it may be constructed as an external device that is carried over the body of the patient.

The operation of the insulin pump can be controlled and modified by means of the control unit. For example, the delivery of adequate amounts of insulin by the insulin pump requires the patient to frequently determine their blood glucose level and enter this value into the control unit, which then calculates an appropriate modification to the default or current protocol. in use of insulin delivery, i.e. dosing and timing, and subsequently communicates with the insulin pump to adjust its operation accordingly. Determination of blood glucose concentration is performed by means of a battery-powered measuring device such as a handheld electronic meter that receives blood samples through enzyme-based test strips and calculates the blood glucose value. based on the enzymatic reaction. Conveniently, the measuring device is an integral part of the blood glucose system, so that the measured value is automatically supplied to the control unit. In this regard, the measuring device can be integrated within the housing of the control unit or it can be provided as a separate device communicating with the control unit. In addition, it may be necessary to use the control unit each time the patient eats to instruct the pump to deliver a specified amount of insulin to cover that meal. Recently, a more or less closed loop control has been performed in which the control unit automatically modifies the insulin delivery protocol.

In view of the permanence of therapy, it is desirable to provide the diabetic patient with flexibility, convenience and ease of use to increase their quality of life. In this regard, it is clear that cable connections between individual devices of the blood glucose system are disadvantageous. Thus, it is known to provide a wireless communication link. However, when implementing wireless communication, it has to be taken into account that the necessary receivers and transmitters are a major source of power consumption. Thus, its use results in reduced battery life and requires replacement or recharging more frequently than individual devices. In medical devices, this issue is not only inconvenient for the patient but also increases the danger that the devices will not function properly when needed. In addition, for devices that are implanted, the replacement or recharging of the battery is accompanied by surgery. Therefore, it is important to provide efficient use of transmitters and receivers.

ES 2 336 360 T3

One possibility to reduce energy consumption is to reduce the transmission power. However, in many applications this is not enough. Thus receivers and transmitters are commonly only regularly activated from time to time during differently spaced listening and transmitting periods, and a means of synchronization is provided which attempts to maintain the coincidence between the listening and transmitting periods. With regard to battery life, it is desirable to reduce the duration of individual listening and transmission periods and to increase the spacing between every two successive periods. Due to the spacing of the listening periods, however, it is no longer possible to transmit a message immediately to a receiver on request. Instead, a device wishing to transmit a message to a particular receiver has to wait at least until the beginning of the receiver's next listening period, and also has to wait for an acknowledgment at least until its next listening interval. Therefore, extended periods during which the receivers are deactivated have the disadvantage that they tend to result in substantial delay times that are inconvenient for the patient. Thus, there is a lower limit below which the spacing between successive listening periods should not fall if a proper compromise between battery life and delay time is to be achieved.

An exemplary blood glucose system in this direction is described in US 6,585,644. This reference describes a battery powered external communications device that communicates wirelessly with at least one battery powered medical device such as an implantable insulin pump and / or a blood glucose detector via telemetry messages. The corresponding communication protocol is designed for low power consumption, in particular for medical devices, as well as for low communication delay times. According to the protocol, in all devices the receiver is activated only during different listening periods separated by periods of inactivity. The length of the listening periods determines the power consumption, and the spacing between successive listening periods determines the delay time. Telemetry messages include a preamble portion that effects the transmission of a preamble signal upon the transmission of a message. The transmission of telemetry messages occurs in the corresponding transmission periods between which the transmitter is deactivated. The devices try to stay in sync with each other so that the transmission and listening periods coincide. In the event of communication failure or loss of synchronization, the transmission periods can be extended or shifted, or the preamble signal can be transmitted over an extended period of time to capture a listening period of the target device. The implantable medical device may have a storage mode into which it can be moved during periods of non-use and in which the spacing between successive periods of listening is substantially increased to conserve battery power. This system has the drawbacks indicated above. It is still desirable to decrease the delay time further without substantially increasing the power consumption.

Document 6,807,159 describes a protocol designed to reduce power consumption in master-led wireless networks without substantially increasing the delay time. The master regularly transmits a polling message to the slave devices which only activate their receivers during the transmission of this message. For each of the slave devices, a probability-based approach is used to predict the arrival time of the next data packet. The result of this prediction is then used to set the polling interval for each of the slave devices. This probability-based adaptive polling interval mechanism can lead to optimization with respect to battery life and delay time if the traffic time distribution of each of the devices is approximately constant. However, the mechanism cannot be conveniently applied to blood glucose systems in which communication between the controller and the other devices in the system takes place only occasionally, so that the distribution of traffic is highly non-uniform.

It is the object of the present invention to provide a method for wireless transmission of data between components of a blood glucose system that combines low energy consumption of all components of the system with low delay times and that remedies the drawbacks encountered in the prior art, and providing the corresponding blood glucose system.

This object is achieved by a method with the features of claim 1 and by a blood glucose system with the features of claim 13. Further preferred embodiments of the invention are the subject matter of the respective dependent claims.

The method steps of the present invention are performed by the components of the blood glucose system that includes an insulin dispensing device and a separate remote controller for wirelessly transferring commands, states, and other data between individual devices in the system. The data flow between the devices follows the master-slave principle, in which the remote controller is the master and the insulin dispensing device and possible additional devices are the slaves that in the usual way never initiate communication but only they respond to messages received from the remote controller, i.e. only the master has the right to initiate a communication cycle, while slave devices only transmit when asked by the master to ensure that two slave devices can never occupy the air interface at the same time. Each of the devices of the blood glucose system includes a receiver and a transmitter for wireless reception and transmission of messages, respectively.

The insulin delivery device normally operates in a power saving mode in which its receiver is activated intermittently at the receiver's activation frequency, the receiver being activated each time for a predetermined listening period and the receiver being deactivated during the Rest of the time. In a realization3

In the preferred setting, the predetermined listening period may be for example 10 msec. In the event that it is intended to use the controller to transmit data to the insulin dispensing device or request a response from the insulin dispensing device, the controller's transmitter is activated for a period to transmit a suitable addressed or intended data frame. for the insulin dispensing device. Obviously, apart from cases where the blood glucose system does not include an additional slave device in addition to the insulin dispensing device or where it is intended to transmit the data frame to all slave devices in the system blood glucose , the data frame preferably includes an indication that the data frame is addressed to the insulin dispensing device. The data frame includes a preamble portion that is adapted so that upon transmission of the data frame a preamble signal is transmitted during a preamble period. All or some of the data frames may be communication initiation data frames. This type of data frame is transmitted by the controller if you want to communicate with the insulin dispensing device. Following transmission of the communication initiation data frame, the controller's transmitter is turned off, and then the controller's receiver is turned on for a response period. In a preferred embodiment, the response period can be for example 50 msec to 500 msec and preferably about 100 msec. In any case, the chosen response period must sufficiently exceed the command processing times of the slave devices and must be short enough to meet the desired performance and sensitivity requirements. In the event that the slave device receives the preamble signal, that is to say at least a part of the preamble included in the preamble portion of the communication initiation data frame, during a listening period, the receiver of the communication device Insulin dispensing remains active until at least a portion of the remainder of the communication initiation data frame has been received by the insulin dispensing device. Following receipt of the intended or addressed communication initiation data frame for the insulin dispensing device, the insulin dispensing device is switched to the communication mode in which its transmitter is activated to transmit a response to the controller. This response is also made up of a data frame and, depending on the type of data frame transmitted by the controller, it may be a mere confirmation of receipt or it may include additional data requested by the controller. The response transmitted by the insulin dispensing device following receipt of the communication initiation data frame indicates to the controller that the insulin dispensing device did indeed receive the communication initiation data frame and switched to mode. Communication. Subsequently or at a later stage, the insulin dispensing device is switched back from the communication mode to the power saving mode.

According to the invention, once the communication mode is switched to the power saving mode the activation frequency of the receiver is initially set to the first frequency value. If no communication initiation data frame is received by the insulin dispensing device during a predetermined power save timeout period, the receiver activation frequency is set to a second frequency value less than the first value. frequency, thereby providing a "high frequency" energy saving mode and a "low frequency" energy saving mode. On the contrary, if a communication initiation data frame has been received, the insulin dispensing device is switched to the communication mode as described above. Thus, each time the insulin dispensing device has received a communication initiation data frame and communicated with the controller, the spacing between successive listening periods is initially chosen so that a very long delay time results. low but slightly higher power consumption than usual. Only after some time without an additional communication initiation data frame addressed or intended for the insulin delivery device from the controller, is the spacing between successive listening periods chosen so that the delay time is increased and the power consumption is lowered from its usual power saving value. This two-stage process is advantageous for the blood glucose system, because the patient usually only uses the controller a few times a day (and general communication between the controller and the insulin delivery device only happens occasionally) , and only during such cases, a high lag time is experienced as a drawback. It has been found that most uses of the controller involve a plurality of messages that are sent from the controller to the insulin dispensing device within a short period of time, i.e., the communication behavior is highly non-uniform. According to the method of the present invention, the delay time is reduced at each of the possible starts of such a high traffic interval.

In the communication initiation data frames, transmitted by the controller, the length of the preamble portion is chosen such that the preamble period exceeds the length of the cycle duration corresponding to the first frequency value. If no response is received during the response period, i.e. in the case where the insulin dispensing device apparently did not receive the preamble signal in one of its listening periods, the length of the preamble portion is increases so that the preamble period exceeds the length of the cycle duration corresponding to the second frequency value, and the communication initiation data frame is retransmitted with this modified preamble portion. Thus, the controller initially transmits the communication initiation data frame so that it is only received if the insulin delivery device is in "high frequency" power save mode or if one of its listening periods overlap with the transmission time of the preamble signal. If the communication initiation data frame is received by the insulin dispensing device, energy is saved because the communication initiation data frame is transmitted with a short preamble period. Only if this communication attempt is unsuccessful is the communication initiation data frame transmitted so that it is finally received by the insulin dispensing device operating in the "low frequency" power saving mode.

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The method of the present invention provides the advantage that for the particular non-uniform traffic pattern of a blood glucose system, low power consumption in both the remote controller and insulin dispensing device is combined with a low response time of the insulin dispensing device for requests transmitted by the controller.

The method of the present invention that can be advantageously applied in the case of the blood glucose system that includes, in addition to the insulin dispensing device, a blood glucose detection device that is also configured as a slave device, and / or possibly one or more additional slave devices. All slave devices of such a system, i.e., the insulin dispensing device, the blood glucose sensing device, and possibly other slave devices, perform the same steps as described above for the insulin dispensing device. . Consequently, with respect to wireless communication, the slave devices show identical behavior, that is, they follow the same communication protocol.

In the case of a blood glucose system comprising more than one slave device, the controller can transmit data to a particular slave device or request a response from a particular slave device as described above for the insulin dispensing device, that is, activating the controller's transmitter during a transmission period to transmit a suitable data frame addressed to this slave device. It is then preferred to include an indication of the target slave device for which the communication initiation data frame is intended in the communication initiation data frame transmitted by the controller to establish communication with the slave device. Once the preamble signal is received by a slave device during one of its listening periods, its receiver remains active until the indication of the target device included in the communication initiation data frame has been received. At this point it can be determined whether the communication initiation data frame is directed to this slave device. Only if the communication initiation data frame is actually addressed to this slave device, does its receiver remain active until the remainder of the communication initiation data frame has been received and the slave device switches to mode. communication as described above. Otherwise, the slave device remains in power saving mode. However, the activation frequency for the slave device is changed to a third frequency value greater than the second frequency value, and only if no communication initiation data frame is received during a predetermined time-out period. , which may be, for example, identical to the above predetermined power saving time-out period, the trigger frequency is changed back to the second frequency value. Thus, each time a communication initiation data frame is received, the slave device reduces the delay time even if the communication initiation data frame is directed to another slave device. This behavior is advantageous because it has been found that during any period of high traffic the controller will probably not only communicate with one slave device but all slave devices in turn. Preferably, the third frequency value and the first frequency value are chosen to be identical.

In a preferred embodiment, the first frequency value is chosen so that the receiver of the insulin delivery device is activated every 100 to 500 msec, preferably every 300 msec, and the second frequency value is chosen so that the receiver of the insulin delivery device is activated every 0.5 to 30 seconds, preferably every 2 to 20 seconds and more preferably about every 3 seconds. In this regard, it is advantageous if the activation period corresponding to the second frequency value is an integer multiple of the activation period corresponding to the first frequency value. It is clear that frequency values ​​are always a compromise between adequate response times and sufficiently low power consumption and have to be chosen to meet particular requirements. On the one hand, higher frequency values ​​increase the power consumption of the slave devices, but reduce the power consumption of the controller, because shorter preamble periods can be used. On the other hand, lower frequency values ​​reduce the power consumption of the slave devices, but result in longer delay times, and because longer preamble periods are required, increased power consumption of the controller results. Furthermore, the short and long preamble periods used by the controller are preferably chosen to exceed the time period of the "high frequency" power save mode and the "low frequency" power save mode, respectively. for approximately 25 msec. Thus, in the most preferred embodiment, the preamble periods are approximately 325 msec and approximately 3025 msec, respectively. Furthermore, it is preferred that the predetermined power saving time-out period is 10 seconds to 60 seconds and preferably about 15 seconds. The optimal value of the predetermined power saving time-out period for a particular application should be chosen on the one hand based on an estimate of the average time period between different user actions on the controller requiring wireless communication, and on the other hand, based on an estimate of the time after which it can be considered that the user will not attempt to invoke another user interaction that requires wireless communication. The above values ​​for the various parameters result in a good balance between low energy consumption and low response time of the blood glucose system.

In the case of more than one slave device, it may be advantageous in some cases if the above method is modified so that once a slave device switches from communication mode to power saving mode, the activation frequency of the receiver is immediately set to the second frequency value without a first setting to the first frequency value. This modified method can be advantageous if in all likelihood the controller sequentially interrogates each of the slave devices exactly once during each

ES 2 336 360 T3 one of the communication periods. In such a case, additional energy savings can be achieved on the side of the slave devices.

The method may involve that all data frames transmitted by the controller are communication initiation data frames. However, it is preferred that the next transmission of a communication initiation data frame the controller also sends additional data frames. Thus, in a preferred version of the method of the present invention, following the transmission of a frame of communication initiation data, the controller transmitter is activated for at least one additional transmission period to transmit at least one additional data frame addressed or intended for the same slave device and including a portion of the preamble that is chosen such that the preamble signal is transmits during a preamble period, and following the transmission of each of the, at least one, Additional data frames the controller receiver is activated during a response period, which in a preferred embodiment may be for example 50 msec to 500 msec, preferably about 100 msec. To provide a possibility for slave devices to distinguish communication initiation data frames from additional data frames and to distinguish between different types of additional data frames, all data frames transmitted by the controller include a command portion in which a command is included that identifies the content of the data frame. For any communication initiation data frame, a communication initiation command is included in the respective command portion to identify this data frame as a communication initiation data frame.

In the event that a slave device receives the preamble signal during a listening period while in power save mode, the receiver of the slave device remains active at least until the command included in the portion of the command has been received. data frame commands, and the slave device remains in power saving mode in case the command is not the communication initiation command. On the contrary, in the event that the slave device receives the preamble signal while in communication mode, the receiver of the slave device remains active at least until the command included in the command portion of the command has been received. the data frame. If the command is not a communication initiation command and the slave device is the intended receiver of the data frame, the receiver of the slave device remains active until the remainder of the data frame has been received, and is then activated and the slave device's transmitter is deactivated to transmit a response to the controller. In this way, slave devices only respond to additional data frames if they are already in communication mode. It should be noted that each of the slave devices transmits a response once they receive the communication initiation data frame which instructs this slave device to switch to the communication mode, i.e. the communication initiation data frame. that starts a communication cycle, as well as every time it receives any additional data frame addressed to this slave device and is received by this slave device while it is still in communication mode. Therefore, in each communication cycle with a particular slave device, all data frames transmitted by the controller for this slave device assume a response data frame transmitted by the slave device to the controller. Depending on the type of data frame transmitted by the controller, the response data frame may be a mere acknowledgment from the receiver or it may include additional data requested by the controller.

In a preferred embodiment, the communication mode in a particular slave device is terminated if no communication initiation data frame or an additional data frame addressed to this slave device is received during a predetermined communication time-out period. , and the communication mode is arranged so that the receiver of the respective slave device remains active as long as its transmitter is not active to transmit a response. Thus, beginning with the reception of the communication initiation data frame a particular slave device is kept in the communication mode for at least a predetermined communication time-out period. In communication mode, the delay time is substantially zero since the receiver of the slave device is active all the time, so that efficient communication involving a plurality of additional data frames and corresponding responses is achieved. In this way, several data frames can be transmitted to the slave device with substantially zero delay time. It is further preferred that the time since the last data frame is transmitted to a particular slave device is tracked in the controller and determined in the controller before transmitting an additional data frame to the same slave device if this device is expected slave is still in communication mode, based on a comparison between the measured time and the predetermined communication timeout period. If it is determined that the slave device is expected to still be in communication mode, the controller initially transmits the data frame so that the preamble period is extended a period of time shorter than the cycle lengths corresponding to the first value. frequency and the second frequency value. In fact, the preamble period can be chosen to have a minimum duration, such as for example about 25 msec, because in communication mode the receiver of the slave device is always activated. In this way, additional energy savings are achieved on the controller side. In a preferred embodiment, the predetermined communication timeout period is 0.2 to 2.5 seconds and preferably about 2 seconds.

In the case of such an extended communication mode, it is further preferred to provide the option of including an indication of a delay time period within the response transmitted by the slave device for a particular first data frame to indicate that the actual response is being received. will broadcast later. In other words, in the event that a slave device determines that it cannot transmit a response within the response period

ES 2 336 360 T3 that follows the transmission of the data frame, may indicate to the controller that there will be a delay in the response. The transmitter and receiver of both the slave device and the controller are then turned off for the indicated delay time period. Only after the end of the indicated delay time period, the transmitter of the controller and the receiver of the slave device are activated, so that the controller can transmit a second frame of data requesting the delayed response from the slave device and the slave device can receive this request. Once the request data frame is received, the slave device's transmitter is activated to transmit the requested response to the controller. Thus, the response period can be chosen to be relatively short to save energy.

In the case of such an extended communication mode in which a communication cycle involves a communication initiation data frame followed by one or more additional data frames, it is advantageous if the data frames transmitted by the controller and by the Slave devices include a frame number or frame reference that uniquely identifies the data frame within a particular communication cycle. For example, the communication initiation data frame may include frame number 1, and the data frame transmitted by the addressed slave device in response to the communication initiation data frame may also include the frame number 1. For each of the additional data frames transmitted by the controller and the corresponding response data frame the corresponding frame number is increased by 1, i.e. the first additional data frame and the response data frame have the number of frame 2, the second additional data frame and the response data frame have frame number 3 and so on. In another example, the communication initiation data frame includes frame number 1, the data frame transmitted by the addressed slave device in response to the communication initiation data frame includes frame number 2, the First additional data frame transmitted by the controller includes frame number 3 and so on. In any case, by means of such frame numbers or frame references it can be ensured that all the commands issued by the controller by means of the transmission of the corresponding data frames are executed exactly once by the addressed slave device in a predetermined order. . The controller knows what frame number or frame reference a response data frame should have that confirms the execution of a command, so the controller can retransmit the command until the execution of the command is confirmed. Also, the slave device knows what frame number or frame reference the additional data frame that corresponds to the next command in a script should have, so it can issue a warning in the event that a command is lost in the script. sequence, and so that a particular command is prevented from executing more than once.

To further increase the security of the blood glucose system, it is also advantageous if each of the data frames not only includes an indication of the addressed slave device (in the case of more than one slave device), but also includes a reference of the source device that uniquely identifies the device (controller or slave device) that transmitted the data frame. This source device reference can be used to ensure that components of a particular blood glucose system discard data frames not belonging to this blood glucose system.

In a further preferred embodiment, the controller may transmit a data frame that includes a termination command to a slave device in communication mode, and the slave device terminates communication mode upon receipt of this termination data frame. Thus, in the event that no attempt is made to use the controller to transmit an additional data frame to a slave device in the communication mode, the communication mode involving a substantially permanently activated receiver may be terminated before the end of the period of communication timeout to save power. This possibility of terminating the communication mode of the slave device is preferably combined with the embodiment described above in which the communication mode in a particular slave device is terminated if no communication initiation data frame or a frame of communication is received. additional data addressed to this slave device during a predetermined communication timeout period. It is then preferred that the communication mode is always terminated by means of a termination command, and that the communication timeout period is only provided as a safety feature to prevent a slave device from inadvertently remaining in the event of errors. the communication mode permanently.

It is further preferred that the transmission of at least one communication initiation data frame by the controller is initiated by user request, that is, the communication initiation data frame is transmitted without waiting for any predetermined transmission window. This may be the case if the patient decides to modify the insulin delivery protocol or change some other slave device setting, or if the patient needs to dispense insulin before a meal.

Additionally or alternatively, it is preferred that a timer event is periodically generated in the controller and that a communication initiation data frame is transmitted by the controller each time such a timer event occurs. In this regard, it is particularly advantageous to choose the frequency at which the timer events occur to have the second value of the frequency or so that the second value of the frequency is an integer multiple of the frequency of the timer events, to include a time reference in each of the communication initiation data frames initiated by a timer event, to examine the time reference once it is received by a slave device, and to synchronize, based on the time reference, the start times of the slave devices' listening periods with the timer events. In this way, regardless of the value of the current activation frequency of a device

ES 2 336 360 T3 target slave, it is ensured that the controller can reach the target slave device using a preamble period that only needs to exceed the length of the cycle duration corresponding to the first value of the frequency. In this way, the energy consumption as well as the delay time are reduced. Transmission caused by the timer event of a communication initiation or self-polling data frame is used for example for automatic control and maintenance of slave devices. In this way, the communication cycles generated by timer events can be used to periodically check the status of the slave devices or to control the operation of the slave devices, for example to regularly dispense adequate amounts of insulin via the dispensing device. insulin. Preferably, such timer events are generated every 3 to 5 minutes, preferably about every 5 minutes. Furthermore, it may be advantageous if the communication initiation data frames transmitted by the occurrence of a timer event are distinguished from the communication initiation data frames initiated by user request, and if the slave device receiving a communication initiation data frame determines whether the communication initiation data frame was initiated by a timer event or by a user request. Thus, the communication timeout period, the power save timeout period and / or the timeout period used by slave devices not addressed by a communication initiation data frame to determine when to switch from the power save mode of "high frequency ”to“ low frequency ”power save mode can be chosen to be shorter for a communication initiation data frame initiated by a timer event than for a frame of communication initiation data initiated by a user request. This can be advantageous, because in most cases the self polling does not require extensive communication and because the self polling does not require user interaction so that the extended delay times do not lead to user nuisance. .

The present invention further relates to the blood glucose system implementing the method of the present invention. Such a system comprises a master controller having a receiver, a transmitter and a control means, in which the control means can be actuated to activate the transmitter during a transmission period to transmit a frame of communication initiation data that includes a preamble portion so that the preamble signal is transmitted during a preamble period, and to subsequently activate the receiver during a response period. The system further includes a slave device comprising insulin dispensing means and having a receiver, transmitter, and control means, wherein the slave device is adapted to be worn or implanted subcutaneously within the body of the patient. patient so that insulin can be delivered from the slave device to the patient's body. The control means of the slave device is adapted to actuate the slave device normally in an energy saving mode in which the control means activates the receiver intermittently at the frequency of activation of the receiver, being activating the receiver each time for a period default listening rate of eg 10 msec and the receiver being turned off for the rest of the time. The control means of the slave device is further adapted to determine whether the receiver of the slave device receives the preamble signal of the communication initiation data frame during a listening period, and whether the signal is received. preamble to keep the slave device receiver active until at least a portion of the remainder of the communication initiation data frame has been received, switching the slave device to the communication mode in which the control means activates the transmitter of the slave device to transmit a response to the controller and subsequently switching the slave device from the communication mode to the power saving mode. The response transmitted by the insulin dispensing device following receipt of a communication initiation data frame indicates to the controller that the insulin dispensing device did indeed receive the communication initiation data frame and switched to mode. Communication.

According to the present invention, the control means of the slave device is adapted to initially set the activation frequency to the first frequency value once the slave device switches from the communication mode to the power saving mode, and to set the trigger frequency to the second frequency value smaller than the first frequency value if the receiver does not receive an intended communication initiation data frame for the slave device during a power saving timeout period predetermined, wherein the control means of the controller is adapted to transmit the communication initiation data frame such that the preamble period exceeds the length of the cycle duration corresponding to the first value of the frequency, and, in the case if you do not receive any response during the response period, adapting and retransmitting the communication initiation data frame so that the preamble period is increased and exceeds the cycle duration length corresponding to the second frequency value.

In a preferred embodiment, the first value of the frequency is chosen so that the receiver of the slave device is activated every 100 to 500 msec, preferably every 300 msec, and the second value of the frequency is chosen so that the receiver of the device slave is activated every 0.5 to 30 seconds, preferably every 2 to 20 seconds and more preferably about every 3 seconds. Furthermore, the short and long preamble periods used by the controller are preferably chosen so that they exceed the time period of the "high frequency" power save mode and the "low frequency" power save mode, respectively, for approximately 25 msec. Thus, in the most preferred embodiment, the preamble periods are approximately 325 msec, and approximately 3025 msec, respectively. Furthermore, it is preferred that the predetermined power save timeout period is 10 seconds to 60 seconds and preferably about 15 seconds. These values ​​result in a good balance between low energy consumption and low response time of the blood glucose system.

ES 2 336 360 T3

In a preferred embodiment, the system includes at least one additional slave device, at least one of which comprises a blood glucose detection means, in which all slave devices comprise a receiver, a transmitter and a configured control means. in the same way as the receiver, the transmitter and the control means, respectively, of the slave device comprising an insulin dispensing means. The control means of the controller is further adapted to include an indication of a target slave device in each communication initiation data frame to individually address the various slave devices. The control means of the slave devices is further adapted to keep the receiver of the slave device active at least until the receiver has received the indication from the target device, and to keep the receiver of the slave device active until the rest of the signal has been received. communication initiation data frame and switch the slave device to communication mode if the slave device is the target slave device, or, In case the slave device is not the target device, keep the slave device in power saving mode, and set the receiver activation frequency for the slave device to the third value of the frequency, which is greater than the second value of the frequency and is preferably identical to the first value of the frequency and subsequently set the activation frequency of the receiver to the second value of the frequency if the receiver does not receive a communication initiation data frame during a predetermined time-out period, in case the control means determines that the slave device receives the preamble signal during a listening period.

It is further preferred that following the transmission of a communication initiation data frame, the control means of the master controller may be further operated to activate the controller's transmitter for at least one additional transmission period to transmit at least one additional addressed or intended data frame for the same slave device and include a preamble portion of mode that the preamble signal is transmitted during a preamble period, and following the transmission of each of the, at least one, Additional data frames activate the controller's receiver for a response period, which may be for example from 50 msec to 500 msec and preferably approximately 100 msec, in which all data frames transmitted by the controller include a portion of commands in which a command is included. The control means of the controller is further adapted to include a communication initiation command in the command portion of any communication initiation data frame to indicate that this data frame is a communication initiation data frame. . The control means of the slave devices is further adapted to determine whether the receiver of the slave device receives the preamble signal during a listening period while in the power saving mode, and if this determination is positive keep the receiver of the slave device active until the command included in the command portion of the data frame has been received, and keep the slave device in power saving mode in case the command is not the communication initiation command. The control means of the slave devices is further adapted to determine whether the receiver of the slave device receives the preamble signal while it is in the communication mode, and in case this determination is positive to keep the receiver of the slave device active when less until the command included in the command portion of the data frame has been received, and if the command is not a communication initiation command and the slave device is the intended receiver of the data frame, keep the receiver of the slave device active until the remainder of the data frame has been received, and activate and disable the slave device's transmitter to transmit a response to the controller. It should be noted that each of the slave devices transmits a response to the receipt of a communication initiation data frame that instructs this slave device to switch to the communication mode, that is, the communication initiation frame that begins a communication cycle, as well as the reception of any additional data frames addressed to this slave device and received by this slave device while it is still in communication mode. Therefore, in each of the communication cycles with a particular slave device, all the data frames transmitted by the controller for this slave device assume a response data frame transmitted by the slave device to the controller. Depending on the type of data frame transmitted by the controller, the response data frame may be a mere acknowledgment of receipt or it may include additional data requested by the controller.

In a further preferred embodiment, the control means of each of the slave devices is adapted to terminate the communication mode if the receiver does not receive a data frame for the respective slave device during a predetermined communication time-out period, and to keep the receiver of the respective slave device active in the communication mode whenever the transmitter is not activated to transmit a response. In a preferred embodiment the predetermined communication timeout period is 0.2 to 0.25 seconds and preferably about 2 seconds.

It is also preferred that the controller further includes a timer, and that the controller's control means is adapted to start the timer once a data frame is transmitted to a particular slave device, to determine, before transmitting a data frame to the same slave device, if the slave device is expected to still be in communication mode based on a comparison between the current value of the timer and the predetermined communication timeout period, and in the event that it is determined that the slave device is expected to still be in the communication mode, initially transmit the data frame so that the preamble period extends a period of time shorter than the cycle durations corresponding to the first frequency value and second frequency value.

It is further preferred that the control means of each of the slave devices is adapted to include an indication of the delay time period within a response transmitted by the slave device to

ES 2 336 360 T3 a particular first data frame to indicate that the actual response will be transmitted later, to deactivate the transmitter and receiver during the indicated delay time period, to activate the receiver of the slave device after the end of the period delay time to wait for the reception of a second data frame requesting the response to the first data frame, and to subsequently activate the transmitter of the slave device to transmit the requested response to the controller, and that the control means of the controller is adapted to deactivate, upon receipt of the response including an indication of the delay time period, the transmitter and the controller receiver for the indicated delay time period, and activating the controller's transmitter after the end of the delay time period to transmit a second data frame requesting the response to the first data frame.

In a preferred embodiment, the control means of the controller can be operated to transmit a data frame including a termination command to a slave device in communication mode, and the control means of each of the slave devices is adapted to terminate communication mode upon receipt of this data frame. This possibility of terminating the communication mode of a slave device is preferably combined with the embodiment described above in which the communication mode in a particular slave device is terminated if no communication initiation data frame or a frame is received. of additional data addressed to this slave device during a predetermined communication timeout period. It is then preferred that the communication mode is always terminated by means of a termination command, and that the communication timeout period is provided only as a safety feature to prevent a slave device from inadvertently remaining in the event of errors. in communication mode permanently.

In a preferred embodiment, the controller comprises actuation means, actuation of which provides a signal to the control means instructing the control means to transmit a data frame.

It is also preferred that the controller further comprises a timer event generator that can be operated to periodically generate a timer event and provide the corresponding timer event signals to the controller's control means, and that the controller's control means is adapted to transmit a communication initiation data frame each time it receives such a timer event signal. In this case, it is further preferred that the frequency with which the timer event generator generates the timer events has the second frequency value, that is such that the second frequency value is an integer multiple of the timer event frequency. , the controller comprises a clock and the control means of the controller is adapted to include a time reference deduced from the clock in each of the data frames initiated by the reception of a timer event signal, and the means of controlling the slave devices is adapted to examine the time reference upon receipt in the slave device, and to synchronize by means of the reference time the start times of the listening periods with the timer events. Preferably, the timer event generator is capable of generating such timer events every 3 to 5 minutes, preferably about every 5 minutes.

In a preferred embodiment, the controller includes a means for detecting blood glucose. Thus, the system may include a slave configured blood glucose sensing device and / or may include a controller within which a blood glucose sensing device is integrated.

In the following, the invention is explained in more detail for a preferred embodiment with reference to the figures.

Figure 1a shows a schematic representation of a blood glucose system according to the present invention.

Figure 1b shows a schematic representation of an additional blood glucose system according to the present invention.

Figure 2a shows a schematic block diagram of the main components of the controller that is part of a blood glucose system according to the present invention.

Figure 2b shows a schematic block diagram of the main components of the slave device that is part of the blood glucose system according to the present invention.

Figure 3a is a schematic flow diagram illustrating the controller side of a preferred embodiment of the method according to the present invention.

Figure 3b is a schematic flow diagram illustrating the slave side of a preferred embodiment of the method according to the present invention.

Figure 4 is a schematic illustration of a data frame.

Figure 5a is a schematic flow diagram illustrating the slave side of a delayed response mechanism.

ES 2 336 360 T3

Figure 5b is a schematic flow diagram illustrating the controller side of a delayed response mechanism.

In Figure 1a a blood glucose system 1 is schematically shown comprising a controller 2, an insulin pump 3 for dispensing insulin into the blood circuit of a patient, and a blood glucose measuring device 4 for determining the level of Blood glucose. Controller 2 includes a housing 5, a display 6 and various control keys 7 that can be used to initiate a particular action by controller 2 or to input data into controller 2, for example to adjust the operation of insulin pump 3 with regard to the various parameters of the patient such as, for example, his weight. Additional major components of controller 2 are depicted in the schematic block diagram shown in Figure 2a. Consequently, the controller 2 further comprises a battery 8, a transmitter 9, a receiver 10, an antenna 11 coupled to the transmitter 9 and the receiver 10, and a clock 23. The operation of the controller 2 is controlled by the control electronics 12 . In particular, the control electronics 12 can be actuated to compose the data frames to be transmitted by means of the transmitter 9, to analyze the data frames received by the receiver 10, and to activate and deactivate the transmitter 9 and the receiver 10 for the transmission and reception of data frames respectively. By means of the clock 23, the control electronics 12 can provide the timer functions (creation, start and stop of the timers) and define and create timer events.

The insulin pump 3 and the blood glucose measuring device 4 each comprise a housing 13, a display 14 and an antenna 15. Additional main components of the insulin pump 3 and the measuring device 4 are represented in the Schematic block diagram shown in Figure 2b. Accordingly, the insulin pump 3 and the measuring device 4 further comprise a battery 17, a transmitter 18 and a receiver 19 which are both coupled to the antenna 15, and a clock 24. The operation of the dildo 2 is controlled by the control electronics 21. In particular, the control electronics 21 can be actuated to compose data frames to be transmitted by means of the transmitter 18, to analyze the data frames received by the receiver 19, and to activate and deactivate the transmitter 18 and the receiver 19 to transmit and receive data frames respectively. By means of the clock 24, the control electronics 12 can provide timer functions (creation, start and stop of timers) and define and create timer events. Both devices also comprise a functional block 20. In the case of the insulin pump 3, the block 20 is an insulin dispensing means, while in the case of the blood glucose measuring device 4, the block 20 is a glucose sensing means that is capable of analyzing blood samples on enzyme-based test strips, which can be inserted into the test strip receiving slot 16, to determine the blood glucose level based on the enzyme reaction. Controller 2 communicates with devices 3 and 4 through RF air interface 22, which can use for example a frequency of 869.84 MHz for Europe and 903.02 MHz for the United States and Canada, a binary separation of 64 KHz and one FSK modulation. Manchester encoding can be used to allow automatic balancing of receivers and to check for Manchester violations. The data rate can be for example 9600 bps.

Figure 1b shows schematically a blood glucose system 1 '. Like system 1 in Figure 1a, system 1' comprises a controller 2 'and an insulin pump 3 for dispensing insulin into the blood circuit of a patient. However the system 1 'does not comprise a separate blood glucose measuring device 4. Instead, the blood glucose measuring means and the test strip receiving slot 16 'are integrated within the controller 2', that is, the controller 2 and the blood glucose measuring device 4 of the system 1. shown in Figure 1a are combined into a single device 2 'having a common housing 5.

In Figures 1a and 1b, the insulin pump 3 is illustrated as an external device to be worn on the body of the patient. However the insulin pump 3 can also be constructed as an implantable device to be disposed subcutaneously.

In the RF wireless network established by controller 2, 2 'and devices 3 and 4, controller 2, 2' is configured as master and devices 3 and are configured as slaves, that is, they never initiate communication but rather they only respond to commands received from controller 2, 2 '. Controller 2, 2 'and slave devices 3, 4 communicate by exchanging data frames, where each transmission preferably consists of only one data frame. One such data frame 300 is shown schematically in Figure 4. The data frame 300 comprises a preamble portion 301, an address header 302 (comprising a target address portion 303, a command portion 304, and a optional additional header portions (not shown) such as a checksum portion, a source address portion and / or a frame number or frame reference portion) and an optional data portion 305. The length of the preamble portion 301 is variable to include an adjustable number of preamble bit octets having a characteristic bit pattern (e.g. 01010101), so that upon transmission of the data frame a signal signal is transmitted characteristic preamble for an adjustable period of time (preamble period). Each of the data frames 300 is addressed to a particular receiver. To indicate the intended receiver, the transmitter includes a predefined target device address within the target address portion 303. The type of data frame, i.e. command or response, and the type of command is identified by a unique identifier. command or response included in command portion 304. In this way, once the data frame 300 has been received, the control electronics 12, 21 can determine whether the respective device is the intended receiver. Furthermore, it can be determined which command or response has been sent by the controller 2, 2 'or the devices 3, 4 respectively. Some commands may require additional information to transmit to the receiver. Such information may be included within the portion of

ES 2 336 360 T3 optional data 305. The same applies to additional information, such as status data, transmitted in response by devices 3, 4.

In Figures 3a and 3b, schematic diagrams of a preferred embodiment of the method according to the present invention are shown, in which Figure 3a shows the steps performed in the controller 2, 2 'and Figure 3b shows the steps performed on the insulin pump 3 and the blood glucose meter 4.

According to the embodiment shown in Figure 3b, the slave devices 3, 4 normally operate in a power saving mode in which their transmitter 18 and receiver 10 are usually deactivated and in which the receiver 19 is only activated every 3 seconds during a listening period of 10 msec. Such mode of operation is commonly referred to as inhalation mode, and the interval between the start times of successive listening periods is referred to as the inhalation interval. Thus, the operation of the slave devices 3,4 begins in step 200, in which the inhalation interval is set to 3 seconds. After the inhalation period has elapsed (step 201), the receiver 19 is activated in step 202, and in step 203 it is determined whether the preamble signal can be detected during the listening period of 10 msec. If this is the case, receiver 19 remains active to receive the remainder of the data frame (step 204). Subsequently, the command portion 304 of the received data frame 300 is examined to determine whether it includes the identifier of the communication initiation command. This particular command is used by the controller 2,2 'to switch the target device to the communication mode in which the receiver 19 is activated essentially all the time. Accordingly, if it is determined in step 206 that the target address portion 303 includes the address of the respective slave device, the receiver is disabled (step 207) and the slave device is switched to the communication mode (step 208).

In communication mode, transmitter 18 turns on and off to transmit a response to controller 2,2 '(step 209), and then receiver 19 turns on again (step 210) to wait for additional data frames 300 from the controller 2,2 '. The response to the communication initiation data frame indicates to the controller 2, 2 'that the slave devices 3, 4 are now in communication mode. In contrast to the inhalation mode, the receiver 19 remains activated until a preamble signal of an additional data frame 300 is detected or until a communication time-out period of for example 2 seconds in duration has elapsed ( ie, longer than the listening period) without detection of the preamble signal (step 211). If a preamble signal of an additional data frame is detected in step 211, the additional data frame is received in step 212. Otherwise, and in the event that none of the received additional data frames were addressed to the slave device, the slave device is switched back to power saving mode (step 214). The same is true if the command contained in the command portion 304 of the additional data frame 300 indicates that the communication mode will be terminated immediately (step 213). However, if the additional data frame 300 received in step 212 is not such a terminating data frame, the receiver 19 turns off at step 214 to return again to step 209 to transmit a response. Depending on the command, such a response may be a mere confirmation of receipt or it may include data requested by the controller 2, 2 '. Thus, as long as the controller 2, 2 'continues to transmit additional data frames 300 to the same slave device 3, 4 so that the preamble signals of the respective additional data frames are received before the expiration of the period of communication timeout, the slave device 3, 4 remains in the communication mode, in which the receiver 19 is only deactivated for the time it takes it to transmit a response. In normal operation, the communication mode is terminated by means of an additional data frame 300 which includes in the command portion 304 a termination command.

Once the communication mode is switched back to the power save mode in step 214, the inhalation interval is set to 300 msec to reduce the lag time in the event of a further communication attempt by the controller. 2.2 '. In step 216, the same is done when a slave device 3,4 receives a data frame 300 that includes the communication initiation command in the command portion 304, and determines in step 206 that the address contained in the portion Address 303 is not your own address.

In any case, following receipt of data frame 300 that is not a communication initiation data frame (step 205) or is a communication initiation data frame addressed to a different device (step 206) , receptor 19 is deactivated for the remainder of the inhalation interval in step 217. Subsequently, it is determined in step 218 whether the inhalation interval is currently 300 msec and whether a predetermined energy saving time-out period of for example 15 seconds has elapsed since the last inhalation interval was set to 300 msec. . Before the end of the waiting time period, the inhalation interval remains unchanged. If it has elapsed, the inhalation interval is left unchanged. If it has elapsed, the inhalation interval is changed to its normal value of 3 seconds in step 219. Thus, as soon as the controller 2, 2 'initiates communication with one of its slave devices 3, 4 the The delay is reduced for all these devices 3, 4, thereby increasing the communication efficiency of the blood glucose system 1, 1 'with its highly non-uniform traffic distribution over the air interface.

With the slave devices 3, 4 operating in this way, in the case where communication is desired between the controller 2, 2 'and one of the devices 3,4, a data frame 300 is prepared on the controller 2, 2 'in step 100 (Figure 3a). Before transmitting the data frame 300, the address of the target device is included within the target address portion 303 (step 101), the identifier of the communication initiation command is included within the command portion 304 (step 102 ), and the number of preamble bit octets is chosen so that the preamble period is 325 msec (step 103). The transmitter 9 is then switched on and off to

ES 2 336 360 T3 transmits this data frame 300, and subsequently the receiver 10 is activated during a response period of 100 msec to wait for a response from the target slave device (eg confirmation of reception). It will be noted that the target slave device 3, 4 will only definitely receive the data frame 300 if its inhalation interval is currently 300 msec. In this case, the preamble period chosen in step 103 extends the entire inhalation interval. However, if the inhalation interval of the slave device 3, 4 is currently 3 seconds, the slave device 3, 4 will probably not detect the preamble signal within one of its listening periods and thus will not send a response. Therefore, if in step 106 it is determined that the slave device 3, 4 has not transmitted a response, the number of octets of bits in the preamble portion 301 of the data frame 300 is increased so as to adjust the preamble period to 3025 msec, that is to say to a value that extends an entire inhalation interval of 3 seconds. Data frame 300 is then retransmitted (step 108) and receiver 10 is activated for 100 msec to wait for a response.

After receiving a response, it is ensured that the respective slave device 3, 4 is in the communication mode with its receiver 19 activated. In this situation, an additional data frame 300 is prepared (step 110), and in step 111, the address of the slave device 3, 4 is included in the address portion 303, a suitable command is included in the command portion 304 and additional data is optionally included in data portion 305. The control electronics 12 in combination with the clock 23 always follow the time since the last data frame is transmitted for the current slave device, and in step 112 the control electronics 12 compares this time with the waiting time period. to determine if the slave device is still in communication mode. If it is determined that the current slave device 3, 4 is still in the communication mode, the preamble period is set to 25 msec in step 114. This minimum preamble period is sufficient since the target slave device is in the mode. so that your receiver 19 is activated. However, it is necessary to transmit the additional data frames well in advance so that the slave device is still in communication mode, that is, the time interval between successive data frames must be less than the timeout period for communication. Otherwise, if the previous determination is negative, the controller returns again to step 100 to initiate another cycle of communication with the slave device (step 113). Next, the additional data frame 300 is transmitted in step 115, followed by activating receiver 9 for 100 msec to wait for a response (step 116). Thus, the target slave has to respond within 100 msec of receiving a data frame. If the controller 2, 2 'does not receive a response within this response time (step 117), it returns again to step 115 to retransmit the additional data frame. If it is determined that additional commands will be transmitted to the same slave device (step 118), an additional data frame 300 is prepared in step 110. Otherwise, a data frame 300 is prepared that includes a termination command in its portion. command line 304 and transmitted to the slave device in step 119 to switch it back to power save mode.

In certain cases, the slave device 3,4 that has just received an additional data frame from the controller 2, 2 ', may not be able to transmit a response within the response time period of the controller 2,2'. For example if the additional data frame includes a command requesting the slave device 3, 4 to collect data and provide this data to the controller 2,2 ', the necessary data may not be immediately available. In such a situation, the slave device 3, 4 has the possibility to delay the transmission of the response in step 209 and instead perform the steps of Figure 5a. Thus, in step 500 it is determined by means of the control electronics 21 whether the data requested by the controller 2, 2 'is currently available. If yes, the method advances to step 209 (step 501). Otherwise, a data frame including an indication of the delay time period is transmitted (step 502), and the receiver 18 and transmitter 19 of the slave device 3, 4 are turned off during the corresponding delay time period (step 503) to save energy. After the delay time period has elapsed (as determined by control electronics 21 in combination with clock 24), receiver 18 is activated in step 504 until an additional data frame is received including a request to transmit the delayed response in step 505. Next, the receiver is turned off at step 506, and the method proceeds to step 209 (step 507) to finally transmit the response to the original additional data frame.

For this delay mechanism to function correctly, the controller 2, 2 'not only determines if a response has been received in step 117 but the control electronics 12 also examines the received response to determine if it includes an indication of the delay time. (which could be represented for example by a suitable command and additional data specifying the delay time period). If no delay time indication is found the method proceeds to step 118 (step 511). On the contrary, in the event that a delay time indication is found, the control electronics 12 effects the deactivation of the receiver 10 and the transmitter 9 for the corresponding delay time period (step 512) to save energy. After the delay time period has elapsed (as determined by the control electronics 12 in combination with the clock 23), the control electronics 12 prepares an additional data frame (step 513), includes an indication of the device target (step 514), and includes a request command and additional data requesting the target slave device to transmit a response to a particular previous data frame (step 515). The preamble period is then set to 25 msec in step 516 (which is sufficient because the target slave device has activated its receiver after the delay time period has elapsed), and the request data frame is transmitted. at step 517. Finally, the method advances to step 116 (step 518) to wait for the requested response.