The handling of glucose and insulin response before and after weight loss with jejuno-ileal bypass: a preliminary report.

Glucose and insulin response were studied in morbidly obese patients before and after jejuno-ileal bypass. Postbypass studies were performed after weight loss greater than 30% (9-48 mon). Six-hour oral glucose tolerance tests were performed on 33 patients before bypass and on 13 of these 33 patients after bypass. Thirteen patients had preoperative intravenous glucose tolerance tests performed, and 11 had postbypass intravenous glucose tolerance tests performed. Plasma insulins were drawn concomitantly. Before bypass, fasting blood sugars and insulins were elevated and both glucose intolerance and hyperinsulinemia were found on the tests. After bypass, oral glucose tolerance test curves were flat (malabsorption effect), while intravenous glucose tolerance tests revealed nonsignificant changes in the glucose curves but plasma insulin response returned toward normal (p greater than 0.05). The glucose intolerance and hyperinsulinemia found in these massively obese patients reverted toward normal after weight loss from jejuno-ileal bypass. Thus elevated plasma insulin does not appear to be a primary etiological factor in obesity.