title: Gastric inhibitory polypeptide and glucagon-like peptide-1 in the pathogenesis of type 2 diabetes.
abstract: The incretin effect denominates the phenomenon that oral glucose elicits a higher insulin response than does intravenous glucose. The two hormones responsible for the incretin effect, glucose-dependent insulinotropic hormone (GIP) and glucagon-like peptide-1 (GLP-1), are secreted after oral glucose loads and augment insulin secretion in response to hyperglycemia. In patients with type 2 diabetes, the incretin effect is reduced, and there is a moderate degree of GLP-1 hyposecretion. However, the insulinotropic response to GLP-1 is well maintained in type 2 diabetes. GIP is secreted normally or hypersecreted in type 2 diabetes; however, the responsiveness of the endocrine pancreas to GIP is greatly reduced. In approximately 50% of first-degree relatives of patients with type 2 diabetes, similarly reduced insulinotropic responses toward exogenous GIP can be observed, without significantly changed secretion of GIP or GLP-1 after oral glucose. This opens the possibility that a reduced responsiveness to GIP is an early step in the pathogenesis of type 2 diabetes. On the other hand, this provides a basis to use incretin hormones, especially GLP-1 and its derivatives, to replace a deficiency in incretin-mediated insulin secretion in the treatment of type 2 diabetes.
authors.affiliation: Diabeteszentrum Bad Lauterberg, Kirchberg 21, D-37431 Bad Lauterberg im Harz. m.nauck@diabeteszentrum.de
authors.forename: Michael A
authors.initials: MA
authors.lastname: Nauck
authors.forename: Birgit
authors.initials: B
authors.lastname: Baller
authors.forename: Juris J
authors.initials: JJ
authors.lastname: Meier
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D005749:Gastric Inhibitory Polypeptide / Q000494:pharmacology / Q000502:physiology*; D005934:Glucagon / Q000502:physiology*; D052216:Glucagon-Like Peptide 1; D006801:Humans; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D010446:Peptide Fragments / Q000502:physiology*; D011498:Protein Precursors / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D007328:Insulin; D010446:Peptide Fragments; D011498:Protein Precursors; D005749:Gastric Inhibitory Polypeptide; D052216:Glucagon-Like Peptide 1; D005934:Glucagon