LIFE-SPAN OF SUBCUTANEOUS GLUCOSE SENSORS AND THEIR PERFORMANCES DURING DYNAMIC GLYCEMIA CHANGES IN RATS

Performances of a glucose sensor have been investigated during dynamic variations of plasma glucose levels. Subcutaneous glucose concentrati ons measured by the sensors were calculated by a one-point calibration , performed in basal conditions. A first group of sensors were chronic ally implanted in the subcutaneous tissue Of normal rats. The animals were submitted to glucagon and insulin injection, in order to induce r apid modifications of their glycaemia. This test was repeated at diffe rent days after implantation in order to investigate the lifespan and the performance of the sensors. All the sensors were working 1 or 2 da ys after implantation, and 70% adequately responded to glycaemia varia tions at day 3 or 4. The quality of the sensors' performance remained constant as a function of the time. With a second group of sensors, we demonstrated that an efficient sterilization procedure did not alter the sensors' characteristics. At the day of implantation, the steriliz ed sensors' performance, during dynamic variations of plasma glucose l evels, was closely similar to that of the non-sterilized sensors. The animals bearing the sterilized devices were rendered diabetic by stept ozotocin (STZ) injection. Once the rats had developed a severe hypergl ycaemia (1-3 days after STZ), they were injected with intravenous insu lin. The subcutaneously implanted glucose sensors correctly followed t he decline in plasma glucose levels. We therefore conclude that our se nsor could represent a useful tool for short-term continuous blood mon itoring.