Incretins are ga rointe inal hormones secreted in response to oral glucose intake in a glucose-dependent manner. The predominant incretins are glucagon-like peptide 1 (GLP1) and glucose-dependent insulinotropic polypeptide (GIP). GLP1 is secreted from endocrine L cells in the ileum and colon, while GIP is secreted from k-cells in the duodenum and jejunum. Interestingly, GLP1 and GIP receptors are widely distributed in various tissues and organs, not only in the pancreas. This indicates extra-pancreatic effects of these hormones.
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