Systems and methods for processing analyte sensor data

• US 8,657,747 B2
• Filed: 04/05/2011
• Issued: 02/25/2014
• Est. Priority Date: 08/22/2003
• Status: Active Grant

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Kamath, Apurv, Li, Ying, Dobbles, John Michael, Mahalingam, Aarthi
• Primary Examiner(s): D'ANGELO, MICHAEL J
• Application Number:
  US13/080,587
• Publication Number:
  US 20110218414A1
• Time in Patent Office: 1,057 Days
• Field of Search: 600/309, 600/316, 600345-347, 600/365
• US Class Current: 600/365
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 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 5/6833 Adhesive patches
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: G16H 40/40 for the management of medical equipment or devices, e.g. scheduling maintenance or upgrades
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

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 processing sensor data, including calculating a rate of change of sensor data and/or determining an acceptability of sensor or reference data.

Claims

1. A method for analyzing data from an analyte sensor, the method comprising:

receiving data from the analyte sensor, the data comprising at least one sensor data point;

receiving reference data from a reference analyte monitor, the reference data comprising at least one reference data point; and

determining, using a processor module, an acceptability of the sensor data or the reference data by subjecting the reference data and substantially time-corresponding sensor data to a boundary test utilizing boundaries defined by predetermined minimum and maximum a priori slope information and a priori baseline information derived from a regression analysis of data obtained prior to insertion of the continuous analyte sensor from at least one of in vitro testing of at least one other continuous analyte sensor or in vivo testing of at least one other continuous analyte sensor;

subsequently forming a conversion function in that defines a slope and a baseline only if the reference data and the substantially time-corresponding sensor data fall within the boundaries, wherein the slope is a calculated amount of electrical current produced by a predetermined amount of the measured analyte, wherein the baseline is a calculated signal contribution due to factors other than the analyte concentration, and wherein both the slope and the baseline are calculated in real-time based on a regression analysis using an equation y=m×

+b, wherein x includes the reference data that fell within the boundaries and y includes the substantially time-corresponding sensor data that fell within the boundaries, wherein m is the slope and b is the baseline; and

converting the at least one sensor data point to an estimated glucose valued based on the conversion function.

2. The method of claim 1, further comprising requesting additional reference data only if the reference data and substantially time-corresponding sensor data do not fall within the boundaries.

3. The method of claim 2, further comprising determining acceptability of the additional reference data, wherein a positive determination of acceptability is determined when the additional reference data and substantially time-corresponding sensor data fall within the boundaries of the boundary test.

4. The method of claim 3, further comprising using the additional reference data for calibration of the analyte sensor in response to a positive determination of acceptability of the additional reference data.

5. The method of claim 3, further comprising using the additional reference data for calibration of the analyte sensor if the additional reference data substantially corresponds to the reference data.

6. The method of claim 1, wherein the determining is performed only if a rate of change of the sensor data is below a predetermined threshold.

7. The method of claim 6, wherein the threshold is 3.5 mg/dL/min or less.

8. The method of claim 6, wherein the rate of change is based on a smoothed rate of change calculation.

9. The method of claim 8, wherein the smoothed rate of change calculation comprises smoothing a plurality of rate of change values.

10. The method of claim 1, wherein the reference analyte monitor is another continuous analyte sensor.

11. The method of claim 10, wherein the continuous analyte sensor and the another continuous analyte sensor are implanted transcutaneously.

12. The method of claim 1, wherein the determining is performed only on the most recently received reference data point.

13. The method of claim 1, comprising identifying sensitivity drift based on the determination.

14. The method of claim 1, comprising identifying baseline drift based on the determination.

15. A system for analyzing data from an analyte sensor, the system comprising:

a sensor data receiving module configured to receive sensor data from the analyte sensor, the sensor data comprising at least one sensor data point;

a reference data receiving module configured to receive reference data from a reference analyte monitor, the reference data comprising at least one reference data point; and

a processor module configured to determine an acceptability of the sensor data or the reference data by subjecting the reference data and substantially time-corresponding sensor data to a boundary test utilizing boundaries defined by predetermined minimum and maximum a priori slope information and a priori baseline information derived from a regression analysis of data obtained prior to insertion of the continuous analyte sensor from at least one of in vitro testing of at least one other continuous analyte sensor or in vivo testing of at least one other continuous analyte sensor, wherein the processor module is configured to subsequently form a conversion function in that defines a slope and a baseline only if the reference data and the substantially time-corresponding sensor data fall within the boundaries, wherein the slope is a calculated amount of electrical current produced by a predetermined amount of the measured analyte, wherein the baseline is a calculated signal contribution due to factors other than the analyte concentration, and wherein both the slope and the baseline are calculated in real-time based on a regression analysis using an equation y=m×

+b, wherein x includes the reference data that fell within the boundaries and y includes the substantially time-corresponding sensor data that fell within the boundaries, wherein m is the slope and b is the baseline, and wherein the processor module is configured to convert the at least one sensor data point to an estimated glucose valued based on the conversion function.

16. The system of claim 15, wherein the processor module is configured to request additional reference data only if the reference data and substantially time-corresponding sensor data do not fall within the boundaries.

17. The system of claim 16, wherein the processor module is configured to determine acceptability of the additional reference data, wherein a positive determination of acceptability is determined when the additional reference data and substantially time-corresponding sensor data fall within the boundaries of the boundary test.

18. The system of claim 17, wherein the processor module is configured to use the additional reference data for calibration of the analyte sensor in response to a positive determination of acceptability of the additional reference data.

19. The system of claim 17, wherein the processor module is configured to use the additional reference data for calibration of the analyte sensor if the additional reference data substantially corresponds to the reference data.

20. The system of claim 15, wherein the processor module is configured to perform the acceptability determination only if a rate of change of the sensor data is below a predetermined threshold.

21. The system of claim 20, wherein the threshold is 3.5 mg/dL/min or less.

22. The system of claim 20, wherein the rate of change is based on a smoothed rate of change calculation.

23. The system of claim 22, wherein the smoothed rate of change calculation comprises smoothing a plurality of rate of change values.

24. The system of claim 15, wherein the reference analyte monitor is another continuous analyte sensor.

25. The system of claim 24, wherein the continuous analyte sensor and the another continuous analyte sensor are implanted transcutaneously.

26. The system of claim 15, wherein the processor module is configured to perform the acceptability determination only on the most recently received reference data point.

27. The system of claim 15, wherein the processor module is configured to identify sensitivity drift based on the determination.

28. The system of claim 15, wherein the processor module is configured to identify baseline drift based on the determination.