"Plasma Insulin Activity' in Human Diabetes During Hypoglycemic Response to Tolbutamide and Indole-3-Acetic Acid

Abstract

Orally administered tolbutamide (3 g) and indole-3-acetic acid (100 mg/kg) depressed fasting glucose levels 22% and 11%, respectively, in 5 normal subjects; 44% and 35% in 7 elderly mild diabetics; and 1% and 1% in 5 uncontrolled juvenile diabetics. Both normal subjects and mild diabetics had significant fasting "plasma insulin activity" (glucose uptake by rat diaphragm), and showed sharply increased insulin activity after ingesting 100 g glucose. Plasma insulin activity was undetectable in juvenile diabetics both before and after glucose. In no individual, normal or diabetic, was the hypoglycemic response to tolbutamide or indole-3-acetic acid accompanied by increased insulin activity in peripheral plasma.