Effect of intravenous glucose infusion on plasma insulin removal rate

We have studied the effects of different intravenous glucose loads on the plasma insulin removal rates of constantly infused porcine insulin in dogs. Insulin removal was studied during infusions of exogenous insulin at rates of 20, 50, and 150 mU/min, and three different glucose loads were given during each of the three insulin infusions. Endogenous insulin secretion was suppressed by the constant administration of epinephrine and propranolol, and thus the resulting plasma insulin concentrations were entirely a function of entry and removal of the exogenously infused insulin. Consequently, at steady-state conditions, any change in rate of insulin removal would result in a reciprocal change in plasma insulin concentration. The steady-state plasma insulin concentrations were unchanged during the three different glucose infusions, and this was true at all three of the different insulin infusion rates. We conclude from the data that the rate of glucose administration and the subsequent blood glucose concentrations are without direct effect on plasma insulin removal.