The goal of the proposed project is the development of an electrochemical glucose sensor which is capable of being implanted into the vascular of extracellular space of a diabetic patient for continuous in vivo monitoring of his blood sugar level. The use of this sensor would eliminate the intermittent withdrawal of blood for glucose assay. Such a sensor, when coupled with an insulin infusion pump and interfaced with a feedback system, would complete the development of an integrated artificial endocrine pancreas. A number of pumps and feedback systems are currently under clinical evaluation in the United States. Central to the artificial pancreas is the glucose sensor which is far behind the other components in its development. The availability of such a sensor would constitute a breakthrough for both clinical practice and basic investigation of diabetes and its associated complications. Potentiodynamic studies in this laboratory have revealed two new distinct low-potential anodic peaks at the smooth Pt electrode that can be utilized for glucose monitoring even in the presence of human serum. This reaction is reproducible since the electrode surface is regenerated by cyclic electrochemical pulsing. The two peaks are located at well defined potentials -0.58 V and -0.43 V vs Ag/AgC1. These potentials are stable and do not shift with increasing glucose concentration. The in vitro study has shown that an electrode using this reaction should be operable at glucose levels up to 400 mg/dl. The specific objectives of the proposed three-year pilot study are: (1) to clearly characterize the mechanism by which these two anodic peaks are generated; (2) to select the proper cyclic voltammetric conditions for the practical development of the sensor; (3) to evaluate the specificity of the anodic peaks for glucose in the presence of potentially interfering substances which might be present in human blood and drugs; (4) to determine if trace amounts of Pt are released during prolonged cyclic voltammetry (possible toxicity); and (5) to fabricate a prototype sensor to be integrated into an existing insulin infusion pump and feedback artificial pancreas system.