In most morbidly obese patients with diabetes, fasting plasma
glucose levels decreased immediately after
jejunoileal bypass operations, with patients often becoming normoglycemic before discharge from the hospital. All 12 patients who had required
insulin or orally administered
hypoglycemic agents preoperatively were able to discontinue the medication shortly after the operation. Oral
glucose tolerance test curves in all morbidly obese patients had a flattened pattern, in the normal range, postoperatively. Serum
insulin levels, which had been elevated preoperatively, decreased significantly, both in fasting and postglucose determinations. Results of intravenous
glucose tolerance tests showed little change in the early period after operation. Improvement in carbohydrate metabolism may be due to several factors and does not appear to be dependent upon massive
weight loss. Major factors may include decreased absorption of
carbohydrates and
amino acids, decreased oral caloric intake, increased
insulin sensitivity and decreased output of
gastric inhibitory polypeptide as well as the eventual
weight loss.