The release of gastric inhibitory peptide, glucagon-like peptide-I, and insulin after oral glucose test in colectomized subjects

BACKGROUND: The physiologic role of the colon as an endocrine organ is not clear. We therefore studied the enteroinsular axis in patients with ulcerative colitis after colectomy.

METHODS: The subjects included 11 patients with a conventional ileostomy, 10 patients with an ileoanal reservoir, and 10 normal controls. The concentrations of glucose, insulin, gastric inhibitory peptide (GIP), and glucagon-like peptide-I (GLP-I) were measured in plasma during an oral glucose test.

RESULTS: The peak level of glucose and peak levels and area under the curve (AUC) of insulin and GIP were higher in patients (P < 0.05). Neither the peak level nor the AUC of GLP-I differed between patients and controls, but time to peak level was four times longer in patients with an ileoanal reservoir (P < 0.05).

CONCLUSION: Colectomy seems to affect the enteroinsular axis, leading to hyperinsulinemia and an impaired glucose tolerance. Moreover, patients with an ileoanal reservoir have a slower GLP-I response after intake of glucose.