Diagnostic Use of Glucagon-Induced Insulin Response

Abstract

The intravenous glucagon stimulation test was assessed as a diagnostic tool in the differential diagnosis of hypoglycemia. Six of seven patients with insulinoma had peak insulin values over 130 µU/ml. None of the controls with normal weight or patients with hypoglycemia as a result of other causes had a peak insulin value over 98 µU/ml. In this study and in glucagon tests done by other investigators, the peak insulin responses occurred from 3 to 30 minutes after injection of glucagon. Since this peak is highly transient it may be missed unless sampling is done every 5 minutes for at least 30 minutes. When done properly, this test was positive in over 80% of insulinoma patients. False-negative results occur in patients treated with diazoxide, hydrochlorothiazide, or diphenylhydantoin. False-positive tests may be seen in individuals who are obese or treated with tolbutamide.