Similar plasma GIP responses in obese and lean subjects after an oral test meal and after intraduodenal stimulation with fat and glucose.

Eight morbidly obese subjects and 12 controls were studied with an oral test meal and a heavy duodenal infusion with fat and glucose. Five of the controls were excluded because of nausea and vomiting after the duodenal stimulation whereas none of the obese subjects noted any discomfort. There was no difference in plasma GIP secretion between the two groups neither after the oral nor after the duodenal stimulation. The present study supports our previous conclusion of an unaltered GIP secretion in obesity.