Overview of incretin hormones.
Incretins are hormones released by nutrients from the GI tract. They amplify glucose-induced insulin release. By raising circulating incretin levels, oral glucose provokes a higher insulin response than that resulting from intravenous glucose. The two most important incretin hormones are glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1). In patients with type 2 diabetes, the incretin effect is decreased, mainly due to loss of the GIP-regulated second phase of insulin secretion, and because of a decreased secretion of GLP-1. In addition to its insulinotropic effect, GLP-1 inhibits glucagon release, prolongs gastric emptying, and leads to decreases in body-weight, all of which explain the marked antidiabetogenic effect of this incretin hormone.
Efendic
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Department of Molecular Medicine, The Endocrine and Diabetes Unit, Karolinska Institutet, SE-17176 Stockholm, Sweden. Suad.Efendic@molmed.ki.se
Portwood
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D000595:Amino Acid Sequence; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology; D005749:Gastric Inhibitory Polypeptide / Q000378:metabolism / Q000502:physiology*; D005934:Glucagon / Q000378:metabolism / Q000502:physiology*; D052216:Glucagon-Like Peptide 1; D006801:Humans; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism / Q000502:physiology*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism / Q000502:physiology*; D011498:Protein Precursors / Q000378:metabolism / Q000502:physiology*
D007328:Insulin; D010446:Peptide Fragments; D011498:Protein Precursors; D005749:Gastric Inhibitory Polypeptide; D052216:Glucagon-Like Peptide 1; D005934:Glucagon