Incretins, which are insulinotropic gastrointestinal hormones, are produced mainly in K and L cells of the small intestine under the influence of nutritional stimuli. The best known incretins are glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). These hormones perform several functions: they stimulate insulin secretion in the pancreatic beta cells; they inhibit glucagon release from the alpha cells of the pancreas (GIP not in humans); they slow down gastric emptying and may directly suppress appetite; and, moreover, they indirectly increase peripheral glucose tolerance/insulin sensitivity. The insulinotropic and glucagonostatic effects of GLP-1 are glucose dependent. The incretins also have numerous other properties which are still being discovered and introduced in different branches of medicine. The patents mentioned in this work concern the use of incretins in diabetology, cardiology, gastroenterology and nuclear medicine. The pleiotropic effects of incretins offer therapeutic possibilities in numerous fields of medicine.