Effect of Gastrointestinal Hormones on Insulin and Glucagon Secretion

Abstract

IT has been well established that the insulin response to orally administered glucose is greater than that to glucose given intravenously.¹ After oral glucose, serum insulin not only rises to higher absolute levels but also remains elevated for a longer time than after intravenous glucose.² Oral glucose administration accelerates the disappearance of a subsequent intravenous glucose load.³ Increased insulin secretion has been also observed after an oral glucose load in subjects with end-to-side portacaval shunts.⁴ However, insulin secretion is similar after injection of glucose into a peripheral vein and into the portal vein during transumbilical portal-vein catheterization,⁵ showing that portal . . .