SYSTEMS AND METHODS FOR DETECTING HYPOGLYCEMIC EVENTS HAVING A REDUCED INCIDENCE OF FALSE ALARMS

• US 20080208026A1
• Filed: 10/30/2007
• Published: 08/28/2008
• Est. Priority Date: 10/31/2006
• Status: Active Grant

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: Lifescan Incorporated (Duv Holding Corporation)
• Inventors: Sharma, Manoj, Horwitz, David, NOUJAIM, Sharbel E., Marhoul, Joseph
• Granted Patent: US 8,439,837 B2
• Time in Patent Office: Days
• US Class Current: 600/365
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B

Abstract

The present invention is directed to a method of reducing false readings in a hypoglycemic detector that includes establishing a predetermined hypoglycemic threshold, a predetermined critical threshold, a predetermined rate of change in glucose concentration where the predetermined critical threshold is below the predetermined hypoglycemic threshold. A first sampling rate is then calculated based upon said predetermined hypoglycemic threshold, said predetermined critical threshold, and said predetermined rate of change in glucose concentration.

Claims

1. A method of reducing false readings in a hypoglycemic detector, said method comprising the steps of:

establishing a predetermined hypoglycemic threshold;

establishing a predetermined critical threshold, said predetermined critical threshold being below said predetermined hypoglycemic threshold;

establishing a predetermined rate of change in glucose concentration; and

calculating a first sampling rate based upon said predetermined hypoglycemic threshold, said predetermined critical threshold, and said predetermined rate of change in glucose concentration.

2. The method according to claim 1, wherein said predetermined rate of change in glucose concentration is a negative rate of change in glucose concentration.

3. The method according to claim 2, wherein said negative rate of change in glucose concentration is based upon a maximum value of an absolute rate observed in people having diabetes.

4. The method according to claim 2, wherein said negative rate of change in glucose concentration is based upon a plurality of previously measured glucose concentrations for a user.

5. The method according to claim 1 further comprising

measuring an actual rate of change in glucose concentration using said first sampling rate;

and

modifying said first sampling rate based upon said actual rate of change in glucose concentration to give a second sampling rate.

6. The method according to claim 5 wherein said second sampling rate is less than said first sampling rate if said actual rate of change in glucose concentration is less than said predetermined rate of change in glucose concentration.

7. The method according to claim 1, wherein said step of establishing a first sampling rate comprises the steps of:

multiplying a preferred number of measurements within a target zone with said predetermined rate of change in glucose concentration to give a product; and

dividing said product by a difference between said predetermined critical threshold and said predetermined hypoglycemic threshold to give the first sampling rate.

8. The method according to claim 1, wherein said step of establishing a first sampling rate is calculated using an equation, said equation being

9. The method according to claim 7 wherein said preferred number is about three.

10. The method according to claim 7 wherein said preferred number of measurements within said target zone is a number of glucose measurements measured within a glucose concentration interval and within a time interval,

said glucose concentration interval is from about said predetermined critical threshold to about said predetermined hypoglycemic threshold, and

said time interval is from a lower time value where said continuous glucose monitor is estimated to measure a glucose concentration at said predetermined hypoglycemic threshold to an upper time value where said continuous glucose monitor is estimated to measure a glucose concentration at said predetermined critical threshold.

11. A method for establishing a critical sampling rate for a continuous glucose monitor comprising the steps of:

establishing a preferred number of measurements within a target zone, a predetermined critical threshold, and a predetermined hypoglycemic threshold;

measuring a plurality of glucose concentrations at a predetermined first sampling rate;

calculating an actual rate of change in glucose concentration based on said plurality of glucose concentrations;

modifying said first sampling rate to a second sampling rate using a function based on said preferred number of measurements within a target zone, said predetermined critical threshold, said predetermined hypoglycemic threshold, and said actual rate of change in glucose concentration.

12. The method according to claim 11, further comprising the step of:

activating a hypoglycemic alarm to detect a hypoglycemic glucose concentration once said first sampling rate is modified to give a second sampling rate.

13. The method according to claim 11, wherein said step of modifying said first sampling rate to said second sampling rate comprises the steps of:

multiplying said preferred number of measurements within a target zone with said actual rate of change in glucose concentration to give a product; and

dividing said product by a difference between said predetermined critical threshold and said predetermined hypoglycemic threshold to give said second sampling rate.

14. The method according to claim 11, wherein said step of modifying said first sampling rate to said second sampling rate using said function based on an equation, said equation being

15. The method according to claim 11 wherein said preferred number is about three.

16. The method according to claim 11 wherein said predetermined critical threshold is about 55 mg/dL and said predetermined hypoglycemic threshold is about 70 mg/dL.

17. The method according to claim 11 wherein said actual rate of change in glucose concentration ranges from about negative 5 milligram per deciliter per minute to about zero milligram per deciliter per minute.

18. The method according to claim 11 wherein said preferred number of measurements within said target zone is a number of glucose measurements within a glucose concentration interval and within a time interval,

said glucose concentration interval is from about said predetermined critical threshold to about said predetermined hypoglycemic threshold, and

said time interval is from a lower time value where said continuous glucose monitor is estimated to measure a glucose concentration at said predetermined hypoglycemic threshold to an upper time value where said continuous glucose monitor is estimated to measure a glucose concentration at said predetermined critical threshold.

19. A continuous glucose monitor comprising:

a sensor portion configured to measure a plurality of glucose concentrations over a period of time;

a memory configured to save said plurality of glucose concentrations, a hypoglycemic threshold, and a critical threshold; and

a microprocessor configured to;

calculate an actual rate of change in glucose concentration per unit time based on said plurality of glucose concentrations; and

calculate a sampling rate based upon said hypoglycemic threshold, said critical threshold, and said rate of change in glucose concentration per unit time

20. The continuous glucose monitor of claim 19 wherein said microprocessor is configured to calculate whether a measured glucose concentration is within a target zone, said target zone comprising:

a glucose concentration interval; and

a time interval,

said glucose concentration interval is from about said predetermined critical threshold to about said predetermined hypoglycemic threshold,

said time interval is from a lower time value where said continuous glucose monitor is estimated to measure a glucose concentration at said predetermined hypoglycemic threshold to an upper time value where said continuous glucose monitor is estimated to measure a glucose concentration at said predetermined critical threshold.

21. The continuous glucose monitor of claim 19, wherein said microprocessor is configured to:

calculate a product by multiplying a preferred number of measurements within a target zone with said actual rate of change in glucose concentration; and

calculate said sampling rate by dividing said product by a difference between said predetermined critical threshold and said predetermined hypoglycemic threshold.

22. The continuous glucose monitor of claim 19, wherein said microprocessor is configured to use an equation to calculate said sampling rate, said equation being

23. The continuous glucose monitor of claim 20, further comprising:

an alarm configured to alert a user that said continuous glucose monitor measured a hypoglycemic glucose concentration that was within said target zone.