Patent ID: 8679016

Claim:
A closed loop system or semi-closed loop system for infusing insulin using sensor values comprising: a first glucose sensor located at a first site generating a first glucose reading; a second glucose sensor located at a second site generating a second glucose reading; a controller configured to perform the steps of: deriving a first predictive value for the first glucose sensor corresponding to the first glucose reading using the second glucose reading as an input, deriving a second predictive value for the second glucose sensor corresponding to the second glucose reading using the first glucose reading as an input, determining a first error between the first predictive value and the first glucose reading, determining a second error between the second predictive value and the second glucose reading, comparing a sum of the absolute error values of the first and the second errors to a threshold, determining a failing sensor exists if the sum of the absolute error values exceeds the threshold, determining whether the first glucose sensor or the second glucose sensor has the least error in the sensor signal if the sum of the absolute error values does not exceed the threshold, calculating a blood glucose value based on the glucose sensor having the least error in the sensor signal, and reporting the calculated blood glucose value; and an infusion pump delivering insulin based on the reported blood glucose value.