Gastric Inhibitory Polypeptide

Abstract

Gastric inhibitory polypeptide (GIP), immunoreactive insulin (IRI), and glucose levels in response to orally administered glucose were determined in ten patients with vagotomy and pyloroplasty (V&P) and in 21 normal subjects. The V&P patients had the expected early and exaggerated increase in mean serum glucose with a subsequent decline to a level below fasting. The early mean GIP response was similarly elevated and paralleled the glucose response. The early mean serum IRI of V&P patients was greater than that of normal subjects, but only at 30 minutes was the difference statistically significant (P<.01). Since GIP is known to be insulinotropic, the results of this study suggest that its role in the enteroinsular axis is magnified after V&P. The GIP may be in part responsible for the postprandial hypoglycemia recognized clinically as the "late phase" of the dumping syndrome.