Incretins in obesity and diabetes

Incretins are hormones secreted from enteroendocrine cells after nutrient intake that stimulate insulin secretion from β cells in a glucose‐dependent manner. Glucose‐dependent insulinotropic polypeptide (GIP) and glucagon‐like peptide‐1 (GLP‐1) are the only two known incretins. Dysregulation of incretin secretion and actions are noted in diseases such as obesity and diabetes. In this review, we first summarize our traditional understanding of the physiology of GIP and GLP‐1, and our current knowledge of the relationships between GIP and GLP‐1 and obesity and diabetes. Next, we present the results from major randomized controlled trials on the use of GLP‐1 receptor agonists for managing type 2 diabetes, and emerging data on treating obesity and prediabetes. We conclude with a glimpse of the future with possible complex interactions between nutrients, gut microbiota, the endocannabinoid system, and enteroendocrine cells.