# US 8,788,006 B2 · System and methods for processing analyte sensor data

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- Number: US 8,788,006 B2
- Document ID: US8788006B2
- Status: Granted
- Kind: B2
- Application number: 12/636,540
- Filed: 2009-12-11
- Published: 2010-07-01
- Granted: 2014-07-22
- Earliest claimed: 2003-08-01
- Assignees: DexCom, Inc.
- Applicants: Apurv Ullas Kamath; Paul V. Goode, Jr.; James H. Brauker
- Inventors: Apurv Ullas Kamath; Paul V. Goode, Jr.; James H. Brauker
- Web page: https://patentgrep.com/patent/US8788006B2

## CPC

- A61B 5/1495: Calibrating or testing of in-vivo probes
- A61B 5/14532: {for measuring glucose, e.g. by tissue impedance measurement}
- A61B 2560/0223: of calibration, e.g. protocols for calibrating sensors
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

Systems and methods for processing sensor analyte data, including initiating calibration, updating calibration, evaluating clinical acceptability of reference and sensor analyte data, and evaluating the quality of sensor calibration. During initial calibration, the analyte sensor data is evaluated over a period of time to determine stability of the sensor. The sensor may be calibrated using a calibration set of one or more matched sensor and reference analyte data pairs. The calibration may be updated after evaluating the calibration set for best calibration based on inclusion criteria with newly received reference analyte data. Fail-safe mechanisms are provided based on clinical acceptability of reference and analyte data and quality of sensor calibration. Algorithms provide for optimized prospective and retrospective analysis of estimated blood analyte data from an analyte sensor.

## Claims

### Claim 1

A method for calibrating a substantially continuous analyte sensor, the method comprising:
receiving a sensor data stream comprising one or more sensor data points from a substantially continuous analyte sensor;
receiving reference data comprising one or more reference data points from a reference analyte monitor;
using a processor module to form at least two matched data pairs by matching reference analyte data to substantially time corresponding sensor data;
using the processor module to form a calibration set comprising the at least two matched data pairs;
using the processor module to create a conversion function based on the calibration set;
using the processor module to convert sensor data into calibrated sensor data using the conversion function;
subsequently receiving an additional reference data point and creating a new matched data pair using the additional reference data point;
using the processor module to evaluate the calibration set with the new matched data pair to ensure the calibration set has substantially distributed high and low matched data pairs over a predetermined time range; and
using the processor module to subsequently modify the conversion function based on the evaluation.

### Claim 2 (depends on 1)

The method of claim 1, wherein receiving the sensor data stream comprises receiving a data stream from an implantable analyte sensor.

### Claim 3 (depends on 1)

The method of claim 1, wherein receiving the sensor data stream comprises receiving a data stream that has been algorithmically smoothed.

### Claim 4 (depends on 1)

The method of claim 1, wherein receiving the sensor data stream comprises algorithmically smoothing the data stream.

### Claim 5 (depends on 1)

The method of claim 1, wherein receiving reference data comprises downloading reference data via a wireless connection.

### Claim 6 (depends on 1)

The method of claim 1, wherein receiving reference data comprises downloading reference data via a wired connection.

### Claim 7 (depends on 1)

The method of claim 1, wherein receiving reference data from a reference analyte monitor comprises receiving within a receiver internal communication from a reference analyte monitor integral with the receiver.

### Claim 8 (depends on 1)

The method of claim 1, wherein the reference analyte monitor is configured for self-monitoring of a blood analyte.

### Claim 9 (depends on 1)

The method of claim 1, wherein using the processor module to create a conversion function comprises performing a linear regression.

### Claim 10 (depends on 1)

The method of claim 1, wherein using the processor module to create a conversion function performing a non-linear regression.

### Claim 11 (depends on 1)

The method of claim 1, wherein using the processor module to create a conversion function utilizes from one matched data pair to six matched data pairs.

### Claim 12 (depends on 1)

The method of claim 1, wherein using the processor module to create a conversion function utilizes at least two matched data pairs.

### Claim 13 (depends on 1)

The method of claim 1, wherein the processor module is incorporated into sensor electronics, receiver electronics or both.

### Claim 14

A system for calibrating a substantially continuous analyte sensor, the system comprising:
a sensor data receiving module configured to receive a sensor data stream comprising one or more sensor data points from a substantially continuous analyte sensor;
a reference data receiving module configured to receive reference data comprising one or more reference data points from a reference analyte monitor; and
a processor module configured to form at least two matched data pairs by matching reference analyte data to substantially time corresponding sensor data, wherein the processor module is configured to form a calibration set comprising the at least two matched data pairs, wherein the processor module is further configured to create a conversion function based on the calibration set, wherein processor module is configured to convert sensor data into calibrated sensor data using the conversion function, wherein the processor module is configured to subsequently receive an additional reference data point and create a new matched data pair using the additional reference data point, wherein the processor module is further configured to evaluate the calibration set with the new matched data pair to ensure the calibration set has substantially distributed high and low matched data pairs over a predetermined time range, and wherein the processor module is further configured to subsequently modify the conversion function based on the evaluation.

### Claim 15 (depends on 14)

The system of claim 14, wherein the sensor data stream is received from an implantable analyte sensor.

### Claim 16 (depends on 14)

The system of claim 14, wherein the sensor data stream is algorithmically smoothed.

### Claim 17 (depends on 14)

The system of claim 14, wherein the processor module is configured to algorithmically smooth said sensor data stream.

### Claim 18 (depends on 14)

The system of claim 14, wherein the reference data receiving module is configured to download the reference data using a wireless connection.

### Claim 19 (depends on 14)

The system of claim 14, wherein the reference data receiving module is configured to download the reference data using a wired connection.

### Claim 20 (depends on 14)

The system of claim 14, wherein the reference data receiving module is configured to receive the reference data a receiver internal communication from a reference analyte monitor integral with said receiver.

### Claim 21 (depends on 14)

The system of claim 14, wherein the reference analyte monitor is configured for self-monitoring of a blood analyte.

### Claim 22 (depends on 14)

The system of claim 14, wherein the processor module is configured to create the conversion function using a linear regression.

### Claim 23 (depends on 14)

The system of claim 14, wherein the processor module is configured to create the conversion function using a non-linear regression.

### Claim 24 (depends on 14)

The system of claim 14, wherein the conversion function is created using from one matched data pair to six matched data pairs.

### Claim 25 (depends on 14)

The system of claim 14, wherein the conversion function is created using at least two matched data pairs.

### Claim 26 (depends on 14)

The system of claim 14, wherein the processor module is incorporated in sensor electronics, receiver electronics or both.