Effects of Tolbutamide and Insulin on Insulin Inhibitory Activity Associated with Plasma Albumin

A reproducible pattern of change in insulin inhibitory activity associated with plasma albumin has been demonstrated. In six normal subjects, intravenous Na tolbutamide increased inhibitor activity to levels seen in many diabetics. Similar increases were seen in certain diabetic patients but not in all. Intravenous exogenous insulin also increased inhibitory activity. Since the latter could be demonstrated in the absence of hypoglycemia, the increase in inhibitor was probably related to the increase in insulin molecules. The time of inhibitor appearance suggests that it may be a product of insulin metabolism but other possibilities exist.