System for regulating the concentration of glucose in the blood of a person

Abstract

The invention relates to a system for regulating the concentration of glucose in the blood of a person, comprising: - a device for selectively supplying at least one and preferably two substances, - at least one and preferably two infusion sets connectable to said device for infusing a said substance to said person; - at least one sensor for measuring a glucose concentration in the blood of said person; - a controller for controlling said device such that a certain amount of a said substance is supplied per time unit and thereby infused into the body of the person via said or a respective infusion set, wherein said certain amount is chosen in accordance with the measured glucose concentration, wherein said controller is arranged to determine a slope of the measured glucose concentration, and wherein the time unit per which the certain amount is supplied is dependent on said slope.

Description

[0001] SYSTEM FOR REGULATING THE CONCENTRATION OF GLUCOSE IN THE BLOOD OF

[0002] A PERSON

[0003] The invention relates to a system for regulating the concentration of glucose in the blood of a person, comprising:

[0004] - a device for selectively supplying at least one and preferably two substances,

[0005] - at least one and preferably two infusion sets connectable to said device for infusing a said substance to said person;

[0006] - at least one sensor for measuring a glucose concentration in the blood of said person;

[0007] - a controller for controlling said device such that a certain amount of a said substance is supplied per time unit and thereby infused into the body of the person via said or a respective infusion set, wherein said certain amount is chosen in accordance with the measured glucose concentration.

[0008] Such a system is known from for example the international patent application with number W02007 / 049961 in the name of the same applicant. W02007 / 049961 in particular teaches a program which incorporates an adjustable glucagon injection curve represented by a first formula (ml(E) / fall mmol / 1 / unit of time) and an adjustable insulin injection curve represented by a second formula (ml(E) / rise mmol / 1 / unit of time) corresponding to an amount of glucagon or insulin respectively introduced into the body of the patient, and the nominal concentration of the glucose in the blood of the patient as a reaction thereto.

[0009] It is an object of the invention to improve the system described in W02007 / 049961 and in particular the program thereof.

[0010] This object is achieved by providing a system according to the preamble, wherein the controller is arranged to determine a slope of the measured glucose concentration, and wherein the time unit per which the certain amount is supplied is dependent on said slope. Alternatively formulated, the frequency with which the certain amount is supplied, for example expressed in number of dosages or units per minute, is dependent on said slope.

[0011] The slope of the measured glucose concentration is defined by the change of measured glucose concentration in time, i.e. the fall or rise of the measured glucose concentration in time. By adjusting or changing the time unit per which the certain amount is supplied in dependence on said slope, a said substance is supplied more or less frequently in dependence of said slope. This is an improvement with respect to the system described in W02007 / 049961, wherein the time unit per which the certain amount is supplied is a fixed time unit and therefore independent of the slope of the measured glucose concentration, because this allows the system to better and / or quicker correct for changes in the glucose concentration in the blood of the person.

[0012] Said slope of the measured glucose concentration may for example be defined in mmol / liter / hour, i.e. the change of measured glucose concentration in mmol / Liter per hour.

[0013] Said at least one and preferably two substances may for example be insulin and glucagon. Said controller may comprise a program comprising the above described adjustable glucagon injection curve represented by a first formula (ml(E) / fall mmol / 1 / unit of time) and the above described adjustable insulin injection curve represented by a second formula (ml(E) / rise mmol / 1 / unit of time), wherein said unit of time per which the glucagon or insulin is injected is adjusted in dependence of said slope.

[0014] Said program may be stored in a memory of said controller.

[0015] The controller may receive the measured glucose concentration from the sensor, wherein the sensor is able to communicate with the controller. Communication preferably takes place wirelessly, for example via a transmitter, but may alternatively take place via a wire.

[0016] In an embodiment of the system according to the invention the time unit per which the certain amount is supplied is decreased in case of a steeper slope, such that in case of a steeper slope the at least one substance is supplied more frequently, and vice versa.

[0017] An advantage of an increase in the frequency of the supply of said substance in case of a steeper slope is that the response of the glucose values to the supply of substance may be quicker. This may prevent excessive glucose values, both at the upper and lower level. A less steep or flat slope implies that the glucose concentration in the blood of the person does not change very quickly such that it is possible to less frequently supply the substance, which may also help keeping the slope flat and thereby the glucose concentration in the blood stable.

[0018] It is noted that a completely flat slope may be defined as a zero slope, and that a steeper slope has a value that deviates from a zero slope, and may be both a positive slope as a negative slope, i.e. a slope having a value above or below zero. For example, the slope may vary between -15 mmol / l / h and 15 mmol / l / h. The steeper the slope, the more the slope deviates from zero.

[0019] As described above, the certain amount of said substance supplied per time unit is chosen in accordance with the measured glucose concentration. If the certain amount is decreased when the frequency of supply is increased, i.e. smaller dosages are supplied more often, the total amount of substance supplied in a certain time frame may remain the same. If the certain amount is not decreased when the frequency of supply is increased, i.e. same size dosages are supplied more often, the total amount of substance supplied in a certain time frame may increase. The average infusion rate in a certain time frame is calculated by multiplying the number of dosages supplied in that time frame by the dosage size. As described above, the average infusion rate may either increase or remain the same if the frequency of supply is increased and may either decrease or remain the same if the frequency of supply is decreased, dependent on the dosage size.

[0020] In order to measure the glucose concentration frequently enough to be able to determine the slope thereof, it is advantageous if said sensor substantially continuous measures said glucose concentration. Said sensor may in particular be a so called Continuous Glucose Monitoring (CMG) sensor for substantially continuously measuring the glucose concentration. Such sensor may for example measure the glucose concentration every few seconds, such as every 5, 10, 15, 20, 25, 30, 40, 45, 50, or 55 seconds, or every few minutes, such as every 1, 2, 3, 4, 5 minutes. It is preferred to measure the glucose concentration at least every 5 or 10 seconds.

[0021] The invention will be further explained with respect to figures in which:

[0022] Figure 1 schematically shows the system according to an embodiment of the invention;

[0023] Figures 2a and 2b show the average infusion rate of two substances respectively in units per minute;

[0024] Figure 3 shows the infusion rates of figures 2a and 2b in a combined figure; and

[0025] Figure 4 shows how the infusion of insulin and glucagon may vary in time in both the amount per dose and frequency of dosing, taking both the glucose concentration in the blood of the person and the slope of the glucose concentration into account.

[0026] Figure 1 shows a system for regulating the concentration of glucose in the blood of a person. The system comprises in this exemplary embodiment a device 1 for selectively supplying in this embodiment two substances contained in respective reservoirs 2, 3, which reservoirs 2, 3 can be received in respective receiving spaces of the device 1. In this embodiment the two substances are insulin and glucagon, respectively. Respective two infusion sets 4, 5 are connected to said device 1 in a fluid communicating manner with the respective reservoirs 2, 3 for infusing a said substance to said person. In this embodiment the infusion sets 4,5 each comprise a respective hose or tube 8,9 for transporting a respective substance to an infusion element 10, 11 of that infusion set 4,5. The infusion elements 10, 11 each comprise a canula 12, 13 which may be inserted into the body of the person for infusing the substance into the body of the person. In this embodiment one sensor 6 for measuring a glucose concentration in the blood of said person is provided. In this embodiment the sensor 6 is shown to be a separate sensor but alternatively the sensor may be combined with one of the infusion sets 4, 5, in particular with the infusion element 10, 11 thereof. It may be preferred to provide two glucose sensors 6, wherein optionally each sensor 6 is combined with a respective infusion set. A controller 7 is provided, in this embodiment as part of the device 1, for controlling said device 1 such that a certain amount of any one of the two substances is supplied per time unit and thereby infused into the body of the person via said or a respective infusion set 4, 5, wherein said certain amount is chosen in accordance with the measured glucose concentration. In accordance with the invention said controller 7 is arranged to determine a slope of the measured glucose concentration, wherein the time unit per which the certain amount is supplied is dependent on said slope, which will be explained with respect to figures 2a, 2b, 3 and 4.

[0027] Figure 2a and 2b respectively show the amount of insulin and glucagon to be injected in dosages or Units (U) / minute into the body of a person in dependence of the measured glucose concentration in mmol / Liter and in dependence of the slope of the measured glucose concentration in mmol / Liter / hour. The slope of the measured glucose concentration is defined by the change of measured glucose concentration in time, i.e. the rise or fall of the measured glucose concentration in time. Figure 2a shows that the number of units per minute supplied to said person increases with increasing slopes, as seen at a certain measured glucose concentration. In other words, the steeper the slope becomes, i.e. a larger deviation from a zero slope, the more frequently insulin and glucagon are supplied, respectively. Figures 2a and 2b show that the slope for insulin lies in this example approximately between 0 and 15 mmol / L / H and that the slope for glucagon lies in this example approximately between 0 and -15 mmol / L / H. Figures 2a and 2b further show that the measured glucose concentration range in which insulin is supplied lies between approximately 6 and 20 mmol / L and for glucagon this range lies between approximately 2 and 5.5 mmol / L. The average dosage rate in units per minute supplied to said person is here both dependent on the measured glucose concentration, i.e. at higher glucose concentration values for insulin and at lower glucose concentration values for glucagon more units per minute are supplied, and on the slope of the measured glucose concentration, i.e. at any given glucose concentration value more units per minute are supplied at steeper slopes.

[0028] Figure 3 shows the curves of figures 2a and 2b in a combined curve.

[0029] Figure 4 shows how the infusion of insulin and glucagon in time may vary in both the amount per dose and frequency of dosing, taking both the glucose concentration in the blood of the person and the slope of the glucose concentration into account. The vertical lines on the horizontal lower axis and in particular the length thereof indicate the number of units or the dosage amount of either insulin or glucagon supplied at a certain time. The number of units to be given at a certain time, i.e. the amount of insulin or glucagon, is chosen in accordance with the measured glucose concentration and may for example be calculated by means of an adjustable glucagon injection curve and an adjustable insulin injection curve corresponding to an amount of glucagon or insulin respectively introduced into the body of the patient, and the nominal concentration of the glucose in the blood of the patient as a reaction thereto. The solid line curve indicates the measured glucose concentration that is used to determine the amount of insulin or glucagon to be supplied and how that varies in time, and in particular may continuously rise and fall. The dotted line curve indicates the slope of the measured glucose concentration, which represents the change of measured glucose concentration in time, i.e. the rise or fall of the measured glucose concentration in time, and shows that when the measured glucose concentration is at a top or bottom, the slope is close to zero. In between the slope deviates from zero, i.e. the slope becomes steeper. This graph shows that if the slope is relatively steep, i.e. deviates from zero either in a positive or negative way, the frequency of dosing increases, because the vertical lines indicating that a dosage of insulin or glucagon is supplied occur more often, i.e. the time between two consecutive dosages is less. When the slope is close to zero, i.e. a relatively flat slope, the time between two consecutive dosages is longer, indicating a lower frequency.

[0030] It is noted that all figures are exemplary only and are only included to show the components of the system and / or how the frequency of insulin and glucagon injection may very in dependence on the slope of the glucose concentration curve. The latter may differ from person to person and from time to time, so the graphs do not indicate real amounts and are exemplary only. It is noted that the invention is not limited to the shown embodiments but also extends to variants within the scope of the appended claims.

Claims

Claims1. System for regulating the concentration of glucose in the blood of a person, comprising:- a device for selectively supplying at least one and preferably two substances,- at least one and preferably two infusion sets connectable to said device for infusing a said substance to said person;- at least one sensor for measuring a glucose concentration in the blood of said person;- a controller for controlling said device such that a certain amount of a said substance is supplied per time unit and thereby infused into the body of the person via said or a respective infusion set, wherein said certain amount is chosen in accordance with the measured glucose concentration, characterized in that said controller is arranged to determine a slope of the measured glucose concentration, and wherein the time unit per which the certain amount is supplied is dependent on said slope.

2. System according to claim 1, wherein the time unit per which the certain amount is supplied is decreased in case of a steeper slope, such that in case of a steeper slope the at least one substance is supplied more frequently, and vice versa.

3. System according to claim 1 or 2, wherein the at least one substance is insulin or glucagon and if the device is arranged for selectively supplying two substances these two substances are insulin and glucagon.

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