A Preliminary Trial of the Programmable Implantable Medication System for Insulin Delivery

We undertook a trial to determine whether an implanted insulin-delivery system, the programmable implantable medication system (PIMS), could be used to treat patients with insulin-dependent diabetes. PIMS is a pulsatile, programmable pump with a battery life expectancy of five years. The reservoir is refilled transcutaneously every two months with a surfactant-stabilized human insulin preparation containing 400 U of insulin per milliliter. Eighteen patients received PIMS-delivered insulin for 4 to 25 months (mean, 18). The total PIMS-implantation experience comprised 28 patient-years. Good glycemic control was established and sustained during treatment (mean plasma glucose level, 7.3 mmol per liter; mean glycohemoglobin level, 8 percent [upper limit of normal, 7.5 percent]), with significantly reduced glycemic fluctuations. The total mean daily insulin dose did not change. Insulin solutions withdrawn from the pump reservoirs contained 92 percent native insulin and preserved biologic activity. There were no surgical or skin complications, severe hypoglycemic episodes, or instances of diabetic ketoacidosis. One pump was replaced because of a manufacturing defect, and four patients had catheter blockages due to omental-tissue encapsulation; two withdrew from the study and two had devices that were repaired successfully. The actuarial rate of survival of catheter function was 78 percent at 1.5 years. We conclude from this pilot study that insulin treatment with an implanted, variable-rate, programmable pump is feasible for periods up to two years. THE continued occurrence of acute and chronic complications of insulin-dependent diabetes mellitus (IDDM), as well as the need for diabetic patients to inject themselves with insulin many times each day, has stimulated research into a more physiologic approach to insulin delivery. Implanted insulin pumps can meet this standard, delivering insulin in selected doses, without daily injections. Such systems could ultimately be connected to implanted glucose sensors, but the first major step is to demonstrate that an openloop implanted pump can be used successfully to treat patients with IDDM. Several attempts to use implanted insulin pumps were made in the early…