The feasibility of intraperitoneal insulin delivery in six healthy, insulin-dependent diabetic men utilizing a preprogrammed, portable insulin pump was examined. Blood glucose concentration was well controlled throughout breakfast, lunch, and supper during the intraperitoneal insulin infusion as assessed by both the mean glucose concentration and the integrated “glucose exposure”. Plasma free insulin concentration demonstrated a meal-related rise and fall similar to that observed in normal, nondiabetic persons. These short-term infusion studies suggest that intraperitoneal insulin may control meal-induced hyperglycemia in diabetic man. More prolonged intraperitoneal infusion studies will be necessary to confirm the feasibility of the peritoneum as an insulin delivery route by an artificial pancreas.