CA2550170A1

CA2550170A1 - Glucose analysis instrument

Info

Publication number: CA2550170A1
Application number: CA002550170A
Authority: CA
Inventors: Karl Werner; Peter Stephan; Robert Lorenz
Original assignee: F Hoffmann La Roche AG
Current assignee: F Hoffmann La Roche AG
Priority date: 2005-06-18
Filing date: 2006-06-14
Publication date: 2006-12-18
Also published as: US20060286620A1; EP1733678A1; US7695677B2; JP4578440B2; ATE547046T1; EP1733678B1; EP1733677A1; JP2006346450A

Abstract

Glucose analysis instrument for diabetics, comprising a measuring device (6) for determining glucose concentration values, a displaying device (4) for displaying glucose concentration values, a signaling device (10) for generating a reminder signal, and a control and evaluation device (7) that comprises a processor and a data memory (8) and is used to determine reminder times at which the signaling device (10) is actuated.
Event time data are stored in the data memory (8), said event time data containing information on events which belong to a predefined event type in the life of a user of the glucose analysis instrument and on the time of occurrence of said events. The reminder times are determined by means of a reminder time determination algorithm taking into consideration event time data from a plurality of days.

Description

Glucose Analysis Instrument to The invention relates to a glucose analysis instrument for diabetics with a signaling device for generating a reminder signal.
In particular, the invention relates to small, battery-operated, portable i5 glucose analysis instruments such as used by diabetics as part of blood glucose self monitoring. Analytical instruments of this type are used to analyze a reaction that proceeds in an analysis element (also called "bio-sensor" or "test strip") after it was made to contact a small drop of the sample liquid. The sample liquid is obtained by means of a skin prick, in ao particular into a finger tip. Depending on the depth of the skin penetration, the sample liquid usually consists of a mixture of blood and interstitial fluid from the skin. Although, accordingly, it is not pure blood that is being analyzed, it is customary to speak of "blood glucose analysis systems". The invention relates in particular to such systems 25 (so-called invasive systems that are customary for self monitoring).
Glucose analysis instruments which additionally comprise a signaling device for generating a reminder signal are commercially available under the trade name "Accu-Check Go". The signaling device of the known 3 o Accu-Check Go glucose analysis instrument can store up to three times of day at which it reminds the user of a required blood glucose measurement by means of an audio signal. The corresponding times of day are selected by the user and entered into the instrument by means of keys.

Since glucose analysis instruments need to be taken along by diabetics at all times, a compact design is required. As a consequence, operating elements such as keys or similar can be provided only in very small form and in small numbers. Consequently, the inputting of times at which an 5 audio signal is to be emitted as a reminder of a blood glucose measurement is difficult and inconvenient. This applies in particular to individuals whose manual abilities are reduced due to age or disease.
US 2003/0175806 A1 describes a blood glucose measuring instrument to that is meant to allow for significantly more frequent determination of the glucose concentration, as compared to customary instruments, in that the measurement is carried out at alternative measuring sites (Alternative Site Testing, AST). The measuring method works without reagents, preferably in a non-invasive fashion. In this context, it is described as an 15 option to carry out additional measurements by means of a conventional invasive ("finger-stick") analysis and to remind the user of the need to carry out a blood analysis measurement at a plurality of times during the day. According to a variant described in this context, the reminder time is not inputted into the instrument (like in the Accu-Check Go), but rather it a o is determined taking into consideration the current glucose value, a nominal glucose value, and measured maximal and minimal values of the measured concentration. The instrument then stores a "case history" of concentration values that were measured which are then used by a processor of the instrument to determine the reminder times by means of a s mathematical prediction methods (e.g. by means of "fuzzy logic").
It is an object of the invention to provide an improved way by which users can be reminded of the need to carry out a blood glucose measurement at individually suitable times.
This object is achieved by a glucose analysis instrument for diabetics, comprising a measuring instrument for determining glucose concentration values, a displaying device for displaying glucose concentration values, a signaling device for generating a reminder signal, and a control and evaluation device that comprises a processor and a data memory and is used to determine reminder times at which the signaling device is actuated, the instrument being characterized in that event time data of a user of the glucose analysis instrument are stored in the data memory, which event type data describe events belonging to a 5 predefined type of event in the daily life of the user and the time of occurrence of such events, and in that the reminder times are determined by means of a reminder time determination algorithm taking into consideration event time data from the same user and from a plurality of days.
to The event time data stored in the data memory of the instrument according to the invention relate to previously selected (pre-defined) types of events in the life of the user. Predefined types of events can, in particular, be measurements of the glucose concentration, food intakes, 15 resting times, and times of increased physical activity. However, in principle, other events that are characteristic of the daily routine of a user, for example start and end of the working hours, can be defined as event types and the corresponding event time data can be stored.
2o In this context, two classes of event types must be distinguished, namely, firstly, types of events that relate to a function of the glucose analysis instrument such that information related to these events is readily available in the analytical instrument ("internal events"), and, secondly, types of events that are characteristic of particularities in the daily routine a5 of the user and do not relate to functions of the glucose analysis instrument such that information related to these events is not readily available (without additional means such as sensors) in the instrument ("external events"). The event time data stored in the data memory of the instrument each contain information regarding the time at which an event 3 o corresponding to a predefined type of event occurs, and information regarding the particular event type.
The stored event times are typically the time of day at which the corresponding event occurs. With. regard to events occurring over an s s extended period of time (such as a food intake or a resting period) the end or the middle of the time over which the event extends, can, for example, be stored as time of the event. Of course, the invention is not limited to a particular form of detecting and storing the timing information which belongs to the event time data. This timing information needs not 5 necessarily be stored as time of day. Rather, it can be favorable, to measure and to store a time period, i.e. the duration between two events, in which case it is not necessary to measure and store the time of occurrence of the event as an absolute value (by time of day and date).
to In particular, the time period between two invents of different event types can be detected and stored. For example, the event time data may comprise the distance in time between a food intake and a glucose measurement. In this case the determination of the reminder times (by the reminder time determination algorithm) is based on the distance in 15 time between the occurrence of the two event types and there is no need to take into account the absolute times of day at which the events occurred. Such a possibility will be further explained below in the context of using an event time as floating reference point.
a o For the event type "measurement of a glucose concentration", the time at which an analysis is carried out is recorded. Obviously, the result of the analysis, i.e. the measured concentration, can additionally be stored.
However, it is preferable to use in the reminder time determination algorithm only the time of day at which the glucose analysis is carried out a 5 and not the result of the analysis.
The information concerning the occurrence of an event that corresponds to an external type can be entered manually by the user by means of an input device of the instrument (e.g. by means of keys). However, the 3 o instrument can also comprise an event sensor that automatically recognizes the event and stores the corresponding event time. Relatively simple and cheap sensors are available, for example, for the detecting physical activity and are used, for example, in step counters. They can be used here to automatically recognize both times of increased physical 35 activity and resting times.

Compared to an instrument with manual input of the reminder times, the glucose analysis instrument according to the invention is characterized by its simplified operation and by the fact that the reminder times are s adapted automatically and flexibly to the daily routine of the user.
Although the method described in US 2003/0175806 A1 also allows an automatic generation of reminder signals, these signals do not adapt to the individual daily routine of the user. Rather, the document attempts to determine reminder times on the basis of analytical results. As part of the to invention, it was noted that this is unsu~able since the reminder time is based on the prediction of the expected future development of the glucose concentration which is associated with great uncertainty.
In a glucose analysis instrument according to the invention, there is no 15 need for the user to enter any times of day into the instrument. The evaluation device independently utilizes data of the previous behavior of the user to determine the times at which the signaling device generates a reminder signal.
a o The reminder function of the instrument independently adapts to the individual daily routine and behavior of a user. It is particularly advantageous that the reminder function independently adapts to a change in the daily rhythm, which may for example be caused by seasonal changes. The reminder function of an instrument according to 25 the invention therefore is a self-learning alarm system reminding the user automatically of measurements of the blood glucose concentration, and possibly other important measures for the treatment of diabetes. The reminder times at which the signaling device is actuated can be determined, for example, by applying a pattern recognition method to the 3 o stored event time data.
In order to determine the reminder times, the control and evaluation device analyzes at least a part of the stored event time data, the event time data used in the analysis being distributed over a plurality of days. It 35 IS preferable to accumulate event time data in the form of daily routine profile data for at least 5, preferably at least 8, particularly preferably at least 12 days and use at least a part of these total data in the reminder time determination algorithm to determine a reminder time.
5 A particular advantage of the invention is that, on the one hand, the reminder times can be determined automatically, and, on the other hand, particularly flexible adaptation to the lifestyle rhythm of the respective user is achieved. In particular relatively young and independent diabetics often have a very irregular daily routine - due to the professional and to personal planning differing from one day to the next. As part of the invention it was found that in these cases a reminder time determination that is oriented on medical measurement results does not provide satisfactory results. The invention allows for flexible combination of various event time data in the reminder time determination algorithm and is thus for adaptation of the reminder times to the individual lifestyle rhythm of the user.
In order to optimize this it is preferable to use different reminder time determination algorithms for working days versus non-working days.
a o Another option for flexible adaptation of the reminder times is to use an event time as a non-static reference point (floating reference point) in the reminder time determination algorithm. Food intakes are particularly well-suited for this purpose. It can be advantageous to determine, in the reminder time determination algorithm, for a plurality of days the period of 25 time between a food intake (for example, lunch) and the subsequent measurement of the glucose concentration and to generate a reminder signal at a point in time that is related to the corresponding food intake (for example, lunch) on the respective day. In the simplest case, the reminder signal may be generated a certain period of time after the 3 0 lunch, with the period of time corresponding to the mean of the periods of time between the blood glucose measurements and the corresponding lunches on the preceding days. Obviously, the mean is only a particularly simple example. Mathematical procedures are available that provide for better adaptation while taking into consideration multiple parameters, i.e.
35 in particular multiple types of events and the respective event time ,data.

The example illustrates, however, that the use of a floating reference point has particular advantages with regard to the flexible adaptation to the habits of the user since the user is reminded of carrying out a glucose measurement not at a more or less fixed time of day, but rather at a point 5 in time that corresponds to his personal daily routine. Here, the time period between the event time used as floating reference point and the reminder time can have any value, including zero. In the last-mentioned case the reminder signal is generated simultaneously with the occurrence of the event which is used as floating reference point.
to Thus the invention allows to determine reminder times that are individually adapted to the daily rhythm of a user and in addition depend on events that are relevant to the time profile of the blood glucose concentration, for example food intakes, insulin administrations or 15 physical activity.
The determination of reminder times as part of the invention is not limited to the timing of required glucose analyses. Rather, other reminder times can also be determined according to the invention, in particular reminder a o signals can be generated as a reminder of insulin administrations and/or food intakes. In this context, it is particularly advantageous to generate different reminder signals with the signaling device. Generally, acoustic signals are preferred, but it is also feasible to use visual reminder signals (for example indicia on a display) or haptic reminder signals (e.g.
a s vibrations).
For example, the control and evaluation device can determine a first class of reminder times at which the signaling device generates a first type of reminder signal as a reminder of a required blood glucose 3 o measurement, and, in addition, generates a second class of reminder times at which the signaling device generates a second type of reminder signal as a reminder of insulin injections, food intakes and/or sports activities.

The invention is illustrated in more detail hereafter by means of an exemplary embodiment with reference to the appended drawings. The particularities shown therein can be used individually or in combination to create preferred embodiments of the invention. In the figures:
Fig. 1 shows a perspective view of a glucose analysis instrument, and Fig. 2 shows a block diagram of the glucose analysis instrument shown in figure 1.
to The external appearance of the glucose analysis instrument 1 shown in figure 1 corresponds to that of known instruments. A displaying device 4 in the form of a display serves to show measuring values. Operating elements 5 in the form of keys are provided for actuating the analytical i5 instrument 1 andlor for special functions. A lancet (not shown) is provided inside the instrument and can be used to generate a prick wound in a body part, for example a finger held against an opening 3 of the housing 2. The instrument 1 takes up blood emerging from the prick wound and uses a measuring device (see figure 2) to determine a blood 2 o glucose concentration value.
The glucose analysis instrument 1 is equipped with a mains-independent power source (not shown), for example commercial batteries, that supplies current to the individual components. The corresponding a5 components of the glucose analysis instrument 1 are known and thus do not need to be illustrated in more detail.
Figure 2 shows a block diagram of the glucose analysis instrument 1 in the form of a schematic representation. The glucose content of a blood s o sample is determined by means of a measuring device 6 that is connected to a control and evaluation device 7. Here, the totality of all components used by the analytical instrument to measure (usually on an analysis element) a physical parameter that is characteristic of the analysis and to determine therefrom the desired glucose concentration is 35 designated "measuring device". A more detailed description is not required in this context, since numerous measuring devices of this type are known and the exact type of the analytical procedure is not important here.
5 The control and evaluation device 7 contains a microprocessor. Glucose concentration values that have been determined are stored in a non-volatile data memory 8 and displayed to a user by means of the display 4.
to Moreover, the glucose analysis instrument 1 is provided with an internal time measuring device 9 that can, for example, utilize a clock generator of the control and evaluation device 7. A signaling device 10 serves to remind a user of the need to carry out a blood glucose measurement, for example by means of an acoustic signal.
In the data memory 8 are stored the measuring times, i.e. the times at which glucose concentration values were measured, in addition to the measured glucose concentration values. The control and evaluation device 7 uses the stored event times to determine reminder times at 2 o which the signaling device 10 is actuated by the control and evaluation device 7. These reminder times are determined by the control and evaluation device 7 using a method (algorithm) that is illustrated hereafter. Initially a very simple method, in which only the event time data of glucose analyses are taken into consideration, will be described.
At the first start-up of the glucose analysis instrument 1, no event time data, i.e. times at which blood glucose measurements were performed, are available. For this reason, the control and evaluation device 7 commences its actual activity only on the second day and accesses the 3 o stored event times, at which blood glucose measurements were performed on the first day. The stored event times of the first day of operation are used as reminder times on the second day of operation.
For this reason, the signaling device 10 is actuated by the control and evaluation device 7 on the second day exactly at the same times of day at which blood glucose measurements were carried out on the first day of operation.
For the third day and all subsequent days of operation, the reminder 5 times are re-calculated. For this purpose, the event times that are within a pre-set time interval from the most recently used reminder time are taken into consideration. The new reminder time is calculated as the mean of these event times.
to The magnitude of this pre-set time interval must be selected such that, for example, event times of the first measurement of a day are not taken into consideration in the calculation of the reminder time for the second measurement of the same day. Accordingly, the time interval should be small enough that only event times of n~" measurements of previous days i5 are contained in the time interval for the calculation of the reminder time of the n'" measurement of a certain day. The time interval preferably comprises approximately one to two hours.
With regard to the calculation of reminder times it is preferable to use only event time data of a limited period of time of, for example, two weeks, such that an adaptation to a changed daily rhythm occurs over a foreseeable period of time. The shorter this period of time, the more rapidly the reminder times will reflect changed lifestyle habits. However, this period of time should not be too short to prevent measurements a s which are for special reasons carried out at uncommon times to have an undesirably large influence on the calculation of the reminder times. It is beneficial to the event time data of the preceding 4 to 14 days in the calculation of the reminder times.
3 o In this context it is advantageous to provide the user with the option to delete stored event time data or to enter such data into the instrument for the first day of operation. For this purpose, the displaying device 4 can be used to display an operating menu from which suitable functions are selected by means of the operating keys 5.

As mentioned, the preceding description concerned a relatively simple reminder time determination algorithm and some variants thereof.
However, considering the processor and data storage capability which is available today even in small, battery-operated instruments, much more 5 sophisticated algorithms can be used. A detailed discussion is not feasible due to the large number of possible variants. Moreover, it is not necessary since the mathematical procedures are known and largely available as commercial program components. The advantages that are associated with the invention and its preferred developments, as to illustrated above, can be achieved with different variants of such commercially available algorithms.
As was illustrated above, the invention is not limited to measurements of the glucose concentration as the type of event. Rather, it is preferable to 15 use event time data of other, in particular of external, types of events.
These can be transmitted to the control and evaluation device 7 either manually by means of an input device 11 or automatically by means of an event sensor 12.
a o Repetition measurements that were carried out, for example, to check outlying measuring values of particularly high or low glucose concentration value, are preferably not used in the determination of reminder times. In this context, it is preferred for the control and evaluation device to compare current glucose concentration values to 25 historical measuring values and, on the basis of this comparison, to independently remind after a pre-set time of, for example, 20 minutes, of the need for a repetition measurement.
Improved convenience for the user can be provided by using a different 3 o reminder time determination algorithm for working days versus non-working days. Most people have a different daily rhythm on working days as compared to non-working days (vacation days, holidays, and weekend days). The simplest way to switch the reminder time determination algorithm between working and non-working days is to have the user s5 instruct the instrument 1 by means of a key stroke whether or not the current day is a non-working day. In a similar manner a specific reminder time determination algorithm can be provided also for other special situations of life, such as times of disease.
5 It is preferable to use the signaling device 10 also to remind a user of a basal injection, i.e. an insulin injection to meet the user's basic need. As the reminder times of blood glucose measurements corresponding reminder times for basal injections can be determined using a reminder time determination algorithm. For this purpose, it is necessary to instruct io the instrument of the point in time of a basal injection. In the simplest case, this can be done by a key stroke such that the time of the key stroke is stored in the data memory 8 as the event time of a basal injection. Preferably, the signaling device 10 generates a different signal as a reminder of a blood glucose measurement than as a reminder of a i5 basal injection. Reminder signals that are easily distinguished by the human ear can be generated, for example, by different sound frequencies or sequences of sounds.
The control and evaluation device 7 can also be used to automatically 2 o remind the user of corrective insulin administrations, food intakes or physical activities taking into consideration event time data (e.g.
concerning insulin administrations, food intakes, and physical activities) and possibly additionally analyzing measuring values of the blood glucose concentration that are stored in the data memory 8.

Claims

1. Glucose analysis instrument for diabetics, comprising:
a measuring device (6) for determining glucose concentration values, a displaying device (4) for displaying glucose concentration values, a signaling device (10) for generating a reminder signal, and a control and evaluation device (7) which comprises a processor and a data memory (8) and is used to determine reminder times at which the signaling device (10) is actuated, characterized in that event time data are stored in the data memory (8), said event time data containing information on events which belong to a predefined event type in the life of a user of the glucose analysis instrument and on the time of said events; and the reminder times are determined by means of a reminder time determination algorithm using event time data from a plurality of days.

2. Glucose analysis instrument according to claim 1, characterized in that event time data are accumulated in the data memory for at least 5, preferably at least 8, particularly preferably at least 12 days during the use of the instrument.

3. Glucose analysis instrument according to any one of the claims 1 or 2, characterized in that internal events of the glucose analysis instrument, in particular glucose concentration measurements, are a pre-defined internal event type of the event time data.

4. Glucose analysis instrument according to claim 3, characterized in that the reminder time determination algorithm comprises a functional step that prevents the actuation of the signaling device (10) at a reminder time if a glucose concentration measurement was carried out in a pre-set waiting period of preferably at least 20 minutes prior to the reminder time.

5. Glucose analysis instrument according to any one of the preceding claims, characterized in that events external to the glucose analysis instrument, in particular food intakes of the user, resting periods of the user, insulin administrations or periods of physical activity of the user, are a predefined external event type of the event time data.

6. Glucose analysis instrument according to claim 5, characterized in that information about the occurrence of an external event type is generated automatically by means of an event sensor.

7. Glucose analysis instrument according to claim 5, characterized in that information about the occurrence of an external event type can be entered manually by means of an input device.

8. Glucose analysis instrument according to any one of the preceding claims, characterized in that the reminder time determination algorithm comprises a pattern recognition method.

9. Glucose analysis instrument according to any one of the preceding claims, characterized in that the reminder times for working days and for non-working days are determined by means of different reminder time determination algorithms.

10. Glucose analysis instrument according to any one of the preceding claims, characterized in that time of an event belonging to a predefined event type, in particular the time of a food intake, is used as a floating reference point in the reminder time determination algorithm,

11. Glucose analysis instrument according to any one of the preceding claims, characterized in that the data memory (8) is non-volatile.

12. Glucose analysis instrument according to any one of the preceding claims, characterized in that the signaling device (10) generates acoustic reminder signals.

13. Glucose analysis instrument according to any one of the preceding claims, characterized in that the control and evaluation device (7) determines a first class of reminder times at which the signaling device (10) generates a first type of reminder signal as a reminder of a blood glucose concentration measurement, and the control and evaluation device (7) determines a second class of reminder times at which the signaling device (10) generates a second type of reminder signal as a reminder of an insulin injection.