The physiologic significance of portal vs. peripheral injection of insulin in man.

The site and rate of entry of insulin into the body may affect its metabolic actions. This study tested for the first time in man the hypothesis that the mode of action of endogenous insulin differs from peripherally injected insulin. In 11 nondiabetic and six diabetic patients we compared the effects on peripheral glucose utilization (PGU) and degree of hypoglycemia of the following: (1) glucagon-free insulin rapidly injected and slowly infused into the portal circulation via percutaneous splenic puncture; (2) peripheral intravenous inslin; (3) peripheral intravenous sodium tolbutamide.