Table 1—

Properties and biological actions of GIP and GLP-1

42–Amino acid peptide30/31–Amino acid peptide
Released from duodenumReleased from distal small bowel and colon
NH2-terminal inactivation by DPP-IVNH2-terminal inactivation by DPP-IV
Stimulates insulin secretionStimulates insulin secretion
Minimal effect on gastric emptyingInhibits gastric emptying
No effect on glucagon secretionInhibits glucagon secretion
No regulation of satiety and body weightInhibits food intake and weight gain
Promotes expansion of β-cell massPromotes expansion of β-cell mass
Normal GIP secretion in diabetic subjectsReduced GLP-1 secretion in diabetic subjects
Defective GIP response in type 2 diabetesPreserved GLP-1 response in type 2 diabetes