Absence of Glucose Response to Physiologic Levels of Serum Insulin

Insulin was given by intravenous injection and infusion into a peripheral vein of dogs to simulate the serum insulin levels obtained following pancreozymin or an intravenous glucose load. A significant change in free fatty acids was obtained without any change in serum glucose. A similar result was obtained by portal vein instillation of insulin. Pancreozymin plus intravenous glucose caused a much higher serum insulin concentration than glucose alone. However, the glucose turnover was the same. It is suggested that the causal relationship of insulin and glucose should be re-evaluated. Hyperinsulinemia in response to hyperglycemia may not be directly related to glucose homeostasis.