In situ calibration of implanted electrochemical glucose sensors

A feasible and reliable method of in situ checking and calibration of implanted glucose sensors is required to compensate for alterations in the overall sensitivity of the "sensor plus subcutaneous fluid glucose compartment" system. In a study on nondiabetic dogs, the linear regression analysis of paired plasma glucose/sensor current data is validated as a potential basis of recalibration of intracorporal glucose sensors. These sensors were amperometric glucose oxidase/hydrogen peroxide electrodes of which the in vitro response time to square alterations in the ambient glucose concentration T95 was less than 5 min. The method presented may be incorporated into the data handling system of portable glucose monitors or of miniaturized artificial beta-cells. For its performance, no steady state glycaemia but a minimum alteration in the intracorporal glucose concentration is needed. The latter can be provided both by tests or by fluctuations as they occur spontaneously during the course of the day.