Pancreatic islet hormone response to oral glucose in morbidly obese patients.

Pancreatic islet peptides, as well as other gastrointestinal hormones, have been implicated in both the pathogenesis of obesity and the etiology of associated metabolic derangements. This study evaluated the pancreatic islet and gastrointestinal (GI) hormone response to oral glucose in 20 morbidly obese (151% above ideal body weight) patients. Glucose intolerance, hyperinsulinism, and exaggerated gastric inhibitory polypeptide (GIP) release occurred following glucose ingestion. Significant release of PP occurred in 14 patients, while only six patients had release of somatostatin. No significant changes in plasma concentrations of glucagon occurred. Since GIP is insulinotropic in the presence of hyperglycemia, the hyperinsulinism of morbid obesity may be secondary to the abnormally high glucose-stimulated GIP levels in these patients. Failure of glucagon suppression in response to oral glucose many contribute to the hyperglycemia noted. Somatostatin and pancreatic polypeptide may be responsible for some of the metabolic derangements of morbid obesity.