THE INSULIN RESPONSE TO GLUCOSE: A COMPARISON BETWEEN ORAL AND INTRAVENOUS TOLERANCE TESTS

Abstract

SUMMARY: Intravenous glucose (25 g.) tolerance tests were performed and plasma insulin levels were determined in 25 normal subjects. There was a direct correlation between the glucose disappearance rate (K value) and the plasma insulin level 10 min. after the glucose injection. Oral glucose (50 g.) tolerance tests were performed in 34 normal subjects with plasma insulin level estimations. The plasma insulin response was slightly greater than that after the intravenous tests although the difference was not significant at the 5% level. Both oral and intravenous tests were performed in the same subjects in 17 instances and the plasma insulin responses in both tests were compared. Nine subjects showed a higher peak insulin response after oral glucose, and eight after intravenous glucose. The intensity and time-course of the insulin response in each individual was similar whether the glucose was given orally or intravenously.