Method and System for Providing Continuous Calibration of Implantable Analyte Sensors

Abstract

Method and system for providing continuous calibration of analyte sensors includes calibrating a first sensor, receiving data associated with detected analyte levels from the first sensor, and calibrating a second sensor based on a predetermined scaling factor and data associated with detected analyte levels from the first sensor, is disclosed.

What is claimed is: 
     
         1 . A method of providing analyte sensor calibration, comprising the steps of:
 receiving data associated with monitored analyte level from a first analyte sensor in fluid contact with interstitial fluid under a skin surface;   receiving data associated with monitored analyte level from a second analyte sensor in fluid contact with the interstitial fluid under the skin surface;   comparing the received data from the first analyte sensor with the received data from the second analyte sensor;   determining a scaling factor based on the comparison and an initial scaling factor;   applying the determined scaling factor to the received data from the second analyte sensor; and   determining a correlation level of signals from the first analyte sensor and the signals from the second analyte sensor.   
     
     
         2 . The method of  claim 1  further including calibrating the second analyte sensor based on the received data from the first analyte sensor. 
     
     
         3 . The method of  claim 1  wherein the scaling factor is based on a predetermined level of average error between the data of the first analyte sensor and the data of the second analyte sensor. 
     
     
         4 . The method of  claim 1  further including initiating the calibration of the second analyte sensor after a predetermined time period has elapsed since the first analyte sensor is maintained in fluid contact with the interstitial fluid. 
     
     
         5 . The method of  claim 4  wherein the predetermined time period includes approximately 90% of the life of the first analyte sensor. 
     
     
         6 . The method of  claim 4  wherein the predetermined time period includes approximately 50% of the life of the first analyte sensor. 
     
     
         7 . The method of  claim 1  further including determining a sensitivity associated with the first analyte sensor. 
     
     
         8 . The method of  claim 1  wherein calibrating the second analyte sensor includes determining an analyte level and comparing the determined analyte level with the data associated with the detected analyte level from the first analyte sensor. 
     
     
         9 . The method of  claim 1  further including comparing the correlation level with a predetermined correlation threshold. 
     
     
         10 . The method of  claim 9  wherein the predetermined correlation threshold defines an acceptable stability level of the second analyte sensor. 
     
     
         11 . The method of  claim 10  wherein when the correlation level is above the predetermined correlation threshold, confirming that the second analyte sensor is stable. 
     
     
         12 . The method of  claim 10  wherein when the correlation level is above the predetermined correlation level, calibrating the second analyte sensor based on one or more detected analyte levels from the first analyte sensor. 
     
     
         13 . The method of  claim 12  wherein calibrating the second analyte sensor includes transferring one or more calibration parameters associated with calibration of the first analyte sensor to the calibration of the second analyte sensor. 
     
     
         14 . The method of  claim 10  wherein when the correlation level is below the predetermined correlation threshold, determining again the correlation level of the signals from the first analyte sensor and the signals from the second analyte sensor. 
     
     
         15 . The method of  claim 1  wherein the scaling factor is determined based on an average of the ratio of the signals from the first analyte sensor and the second analyte sensor. 
     
     
         16 . The method of  claim 1  wherein a predetermined level of average error between the data of the first analyte sensor and the second analyte sensor includes a lowest level of average error. 
     
     
         17 . The method of  claim 1  further including outputting information associated with the monitored analyte level by one or more of the first analyte sensor and the second analyte sensor. 
     
     
         18 . The method of  claim 1  further including performing initial calibration of the first analyte sensor based on a reference measurement. 
     
     
         19 . The method of  claim 18  wherein the reference measurement is obtained before the first analyte sensor is in fluid contact with the interstitial fluid. 
     
     
         20 . The method of  claim 1  wherein the second analyte sensor is calibrated in real time when the second analyte sensor is positioned in fluid contact with the interstitial fluid under the skin layer.