Figure 4.
Actions of gastrointestinal hormones on key tissues in glucose homeostasis. Both GIP and GLP-1 promote insulin biosynthesis, insulin secretion, and islet β-cell survival. GLP-1 exerts additional actions, including inhibition of glucagon secretion and gastric emptying, and induction of food intake. GIP has a direct effect on adipocytes coupled to energy storage. In contrast, CCK and gastrin do not regulate plasma glucose levels but could be important for stimulation of islet neogenesis. Reprinted with permission from Girard J. The incretins: from the concept to their use in the treatment of type 2 diabetes. Part A: incretins: concept and physiological functions. Diabetes Metab. 2008;34(6 Pt 1):550–559.39 Copyright © 2008 Elsevier.
Abbreviations: CCK, cholecystokinin; GIP, glucose-dependent insulinotropic polypeptide; GLP-1, glucagon-like peptide-1.