Transcutaneous analyte sensor
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.
1. A method for monitoring a glucose concentration in a host, the method comprising:
receiving sensor data indicative of a glucose concentration in a host over a period of time, wherein the sensor data is generated by a substantially continuous glucose sensor;
receiving reference data from a reference analyte monitor; and
using a processor module to:
determine a first rate of change of a glucose concentration of a host that is substantially time corresponding to a first reference data point of the reference data;
determine whether the first rate of change is within a range of rates of change delimited by maximum normally sustainable rates of change of glucose in humans; and
calibrate the sensor data using the first reference data point only if the first rate of change is determined to be within the range of rates of change delimited by maximum normally sustainable rates of change of glucose in humans.
2. The method of claim 1 , wherein the maximum normally sustainable rates of change of glucose in humans is within of a range of about +/−4 mg/dL/min.
3. The method of claim 1 , wherein the reference data comprises a data point indicative of a glucose concentration measured by an in vitro single point glucose monitor.
4. The method of claim 1 , wherein using the processor module to calibrate the sensor data comprises:
matching the first reference data point with a time-corresponding sensor data point of the sensor data;
forming or modifying a conversion function based at least in part of the matched data; and
converting the sensor data to glucose values using the formed or modified conversion function.
5. The method of claim 1 , wherein using the processor module to calibrate comprises evaluating a concordance of the sensor data and the first reference data point of the reference data.
6. The method of claim 1 , wherein using the processor module to calibrate comprises evaluating a clinical acceptability of a deviation of the first reference data point from a time-corresponding sensor data point of the sensor data and a risk of the deviation based on a glucose value indicated by at least one of the sensor data or the reference data.
7. The method of claim 1 , wherein using the processor module to calibrate comprises using in vitro sensitivity information.
8. The method of claim 1 , wherein using the processor module to determine the first rate of change is based on first sensor data of the sensor data generated during a first time period, the method further comprising determining a second rate of change based on second sensor data of the sensor generated during a second time period,
wherein the first rate of change is determined not to be within the range of rates of change delimited by maximum normally sustainable rates of change of glucose in humans, and
wherein the second rate of change is determined to be within the range of rates of change delimited by maximum normally sustainable rates of change of glucose in humans.
9. The method of claim 1 , wherein the first rate of change is determined using at least some of the sensor data.
10. The method of claim 8 , wherein using the processor module to calibrate comprises calibrating the at least some of the sensor data using a second reference data point of the reference data and not calibrating the sensor data using the first reference data point.
11. The method of claim 8 , wherein the second reference data point time corresponds to the second rate of change.
12. The method of claim 9 , wherein the at least some of the sensor data is calibrated sensor data.
13. A system for monitoring a glucose concentration in a host, the system comprising:
a receiving module configured to receive sensor data indicative of a glucose concentration in a host over time generated by a substantially continuous glucose sensor and reference data from a reference analyte monitor; and
a processor module configured to:
determine a first rate of change of a glucose concentration of a host that is substantially time corresponding to a first reference data point of the reference data;
determine whether the first rate of change is within a range of rates of change delimited by maximum normally sustainable rates of change of glucose in humans; and
calibrate the sensor data using the first reference data point only if the first rate of change is determined to be within the range of rates of change delimited by maximum normally sustainable rates of change of glucose in humans.
14. The system of claim 13 , wherein the maximum normally sustainable rates of change of glucose in humans is within of a range of about +/−4 mg/dL/min.
15. The system of claim 13 , wherein the reference data comprises a data point indicative of a glucose concentration measured by an in vitro single point glucose monitor.
16. The system of claim 13 , wherein the processor module is configured to calibrate the sensor data by:
matching the first reference data point with a time-corresponding sensor data point of the sensor data;
forming or modifying a conversion function based at least in part of the matched data; and
converting the sensor data to glucose values using the formed or modified conversion function.
17. The system of claim 13 , wherein the processor module is further configured to evaluate a concordance of the sensor data and the first reference data point of the reference data.
18. The system of claim 13 , wherein the processor module is further configured to evaluate a clinical acceptability of a deviation of the first reference data point from a time-corresponding sensor data point of the sensor data and a risk of the deviation based on a glucose value indicated by the sensor data and/or the reference data.
19. The system of claim 13 , wherein the processor module is further configured to use in vitro sensitivity information during the calibrating.
20. The system of claim 13 , wherein the processor module is configured to determine the first rate of change based on first sensor data of the sensor data generated during a first time period, and wherein the processor module is further configured to determine a second rate of change based on second sensor data of the sensor generated during a second time period.
21. The system of claim 13 , wherein the first rate of change is determined using at least some of the sensor data.
22. The system of claim 20 , wherein a second reference data point of the reference data substantially time corresponds to the second rate of change.
23. The system of claim 21 , wherein the at least some of the sensor data is calibrated sensor data.
24. The system of claim 22 , wherein the calibrating comprises calibrating at least some of the sensor data using a second reference data point of the reference data and not calibrating the sensor data using the first reference data point when the first rate of change is determined to be outside the range of rates of change delimited by maximum normally sustainable rates of change of glucose in humans and the second reference data point is determined to be within the range of rates of change delimited by maximum normally sustainable rates of change of glucose in humans.