TRANSCUTANEOUS ANALYTE SENSOR

• US 20070203966A1
• Filed: 03/23/2007
• Published: 08/30/2007
• Est. Priority Date: 08/01/2003
• Status: Active Grant

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Brister, Mark, Brauker, James, Goode, Paul, Kamath, Apurv
• Granted Patent: US 8,275,437 B2
• Time in Patent Office: Days
• US Class Current: 708/200
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2560/0252 using ambient temperature
• CPC Class Codes: A61B 2560/04 Constructional details of apparatus
• CPC Class Codes: A61B 2562/085 combined with means for recording calibration data
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/4839 combined with drug delivery
• CPC Class Codes: A61B 5/6833 Adhesive patches
• CPC Class Codes: A61B 5/6848 Needles
• CPC Class Codes: A61B 5/743 Displaying an image simultaneously with additional graphical information, e.g. symbols, charts, function plots

Abstract

The present invention relates generally to systems and methods for measuring an analyte in a host. More particularly, the present invention relates to systems and methods for transcutaneous measurement of glucose in a host.

Claims

1. A method of calibrating a glucose measuring device in a host, the method comprising:

generating a signal from a continuous glucose measuring device indicative of a glucose concentration in a host;

calculating a rate of change of the signal;

determining a reference value from reference data obtained using a reference glucose measuring device; and

calibrating the signal to obtain a calibrated signal, wherein the step of calibrating comprises using the reference value only when the rate of change of the signal is less than a predetermined threshold.

2. The method of claim 1, wherein the step of determining a reference value comprises determining a reference value using a single point glucose monitor.

3. The method of claim 2, wherein the single point glucose monitor is built-in with at least a portion of the continuous glucose measuring device.

4. The method of claim 1, wherein the reference glucose measuring device is a continuous glucose measuring device.

5. The method of claim 1, wherein the step of calibrating is performed prospectively.

6. The method of claim 1, wherein the step of calibrating is performed during initialization of the continuous glucose measuring device.

7. The method of claim 1, wherein the step of calibrating is performed after initialization of the continuous glucose measuring device.

8. The method of claim 1, wherein the step of calibrating is performed using a single reference value.

9. The method of claim 1, wherein the step of calibrating is performed using more than one reference value.

10. The method of claim 1, wherein the predetermined threshold is a rate of change of glucose concentration of at least about 1.5 mg/dL/min.

11. The method of claim 1, wherein the signal comprises a raw signal, and wherein the step of calculating a rate of change of the signal comprises calculating a rate of change of the raw signal.

12. The method of claim 1, further comprising filtering the signal to obtain a filtered signal, wherein the step of calculating a rate of change of the signal comprises calculating a rate of change of the filtered signal.

13. The method of claim 1, wherein the step of calculating a rate of change of the signal comprises calculating a rate of change of the calibrated signal.

14. The method of claim 1, further comprising a step of predicting a future value indicative of a glucose concentration in the host for at least one of a future time point or a future time period.

15. The method of claim 15, where the step of predicting a future value is based at least in part on the reference data.

16. A device comprising a computer readable memory comprising code for calibrating glucose data from a continuous glucose measuring device, wherein the code comprises:

instructions configured to process glucose data received from a continuous glucose measuring device;

instructions configured to calculate a rate of change of the glucose data from the continuous glucose measuring device; and

instructions configured to receive and calibrate the glucose data using a glucose concentration measured by a reference glucose measuring device only when the rate of change of the glucose data is less than a predetermined threshold, whereby calibrated glucose data is obtained.

17. The device of claim 16, wherein the instructions configured to receive and calibrate the glucose data comprise instructions configured to prospectively calibrate the glucose data.

18. The device of claim 16, wherein the instructions configured to receive and calibrate the glucose data comprise instructions configured to calibrate during initialization of the continuous glucose measuring device.

19. The device of claim 16, wherein the instructions configured to receive and calibrate the glucose data comprise instructions configured to calibrate after initialization of the continuous glucose measuring device.

20. The device of claim 16, wherein the instructions configured to receive and calibrate the glucose data comprise instructions configured to calibrate the glucose data based on a single reference value.

21. The device of claim 16, wherein the instructions configured to receive and calibrate the glucose data comprise instructions configured to calibrate the glucose data based on more than one reference value.

22. The device of claim 16, wherein the predetermined threshold is a rate of change of glucose concentration of at least about 1.5 mg/dL/min.

23. The device of claim 22, wherein the predetermined threshold is a rate of change of glucose concentration of at least about 2.5 mg/dL/min.

24. The device of claim 23, wherein the predetermined threshold is a rate of change of glucose concentration of at least about 3.5 mg/dL/min.

25. The device of claim 16, wherein the instructions configured to process the glucose data received from the continuous glucose measuring device are configured to provide a raw glucose data signal, and wherein the instructions configured to calculate a rate of change are configured to calculate a rate of change of the raw glucose data signal.

26. The device of claim 16, wherein the instructions configured to process the glucose data received from the continuous glucose measuring device are configured to provide a filtered or averaged glucose data signal, and wherein the instructions configured to calculate a rate of change are configured to calculate a rate of change of the filtered or averaged glucose data signal.

27. The device of claim 16, wherein the instructions configured to calculate a rate of change are configured to calculate a rate of change of the calibrated glucose data.

28. The device of claim 16, further comprising instructions configured to predict a future value indicative of a glucose concentration for a future time period or time point.

29. The device of claim 28, wherein the instructions configured to predict a future value indicative of the glucose concentration is based at least in part on the glucose concentration measured by the reference glucose measuring device.

30. A device configured to continuously measure an analyte in a host, the system comprising:

a sensor configured to provide a signal indicative of an analyte concentration in a host; and

a processor operably connected to the sensor and comprising programming configured to determine a rate of change of the signal, wherein the processor further comprises programming configured to receive and process reference data from a reference analyte monitor, and wherein the processor further comprises programming configured to calibrate the signal based at least in part on the reference data.

31. The system of claim 30, wherein the sensor is a glucose sensor, and wherein the programming is configured to accept a reference value for calibration of the sensor only when the signal indicates the rate of change of glucose concentration that is less than about 1 mg/dL/min.

32. The system of claim 31, wherein the programming is configured to accept a reference value for calibration of the sensor only when the signal indicates the rate of change of glucose concentration that is less than about 2 mg/dL/min.

33. The system of claim 32, wherein the programming is configured to accept a reference value for calibration of the sensor only when the signal indicates the rate of change of glucose concentration that is less than about 3 mg/dL/min.

34. The system of claim 30, wherein the processor further comprises programming configured to request reference data from the host.

35. The system of claim 34, wherein the system further comprises a user interface, and wherein the programming configured to request reference data from the host comprises programming configured to relay the request for reference data via the user interface.

36. The system of claim 34, wherein the programming configured to request reference data from the host is configured to avoid requesting reference data during one or more predetermined events, wherein the predetermined events are selected from the group consisting of meal intake above a predetermined amount, exercise above a predetermined amount, analyte concentration outside of a predetermined range, rate of change above a predetermined threshold, rate of acceleration above a predetermined amount, and rate of deceleration above a predetermined amount.

37. The system of claim 34, wherein the programming configured to request reference data from the host is configured to avoid requesting reference data during one or more predetermined events, wherein the predetermined events are selected from the group consisting of interrupted data signal, noisy data signal, and faulty data signal.

38. The system of claim 34, wherein the programming configured to request reference data from the host is configured to request reference data during one or more predetermined events, wherein the predetermined events are selected from the group consisting of analyte concentration within a predetermined range, rate of change below a predetermined threshold, and conducting an assessment of clinical risk of reference data with time-corresponding sensor data.

39. The system of claim 38, wherein the sensor is a glucose sensor and wherein the programming configured to request reference data from the host is configured to request reference data when the rate of change is below a predetermined threshold.

40. The system of claim 30, wherein the processor further comprises programming configured to validate or guide calibration responsive to prior information stored in the processor prior to initialization of the sensor in the host.

41. The system of claim 30, wherein the programming configured to determine a rate of change of the signal is configured to determine a rate of change of raw data associated with the signal.

42. The system of claim 30, wherein the programming configured to determine a rate of change of the signal is configured to determine a rate of change of filtered data associated with the signal.

43. The system of claim 30, wherein the programming configured to determine a rate of change of the signal is configured to determine a rate of change of calibrated data associated with the signal.

44. The system of claim 30, wherein the processor further comprises programming configured to predict a future value of the analyte concentration.

45. The system of claim 44, wherein the programming configured to predict a future value of the analyte concentration is based at least in part on the reference data.