Gastric inhibitory polypeptide (GIP), gastrin and insulin: response to test meal in coeliac disease and after duodeno-pancreatectomy.
The response of serum immunoreactive gastric inhibitory polypeptide (IR-GIP), gastrin (IRG) and insulin (IRI) to a mixed standard meal was measured in 15 controls, 6 patients with coeliac disease, 26 patients with chronic pancreatitis and partial duodenopancreatectomy (Whipple's procedure). Serum levels of IR-GIP, IRG and IRI were significantly reduced in patients with coeliac disease. The serum glucose increase was significantly smaller only during the first hour after the meal. Since small intestinal GIP- and G-cells are situated mainly in the glands of duodenal and jejunal mucosa their absolute number is not significantly reduced in coeliac disease. It is suggested that the release of IR-GIP and duodenal IRG is influenced by the rate of absorption of nutrients. In patients with chronic pancreatitis the IR-GIP release is significantly greater than in controls, the IRG release normal and the IRI response delayed. After Whipple's procedure the IR-GIP response is increased significantly while the IRG secretion is abolished. This demonstrates that the duodenum is not necessary for GIP release and that pancreatic and jejunal gastrin are without clinical significance.