Glucose-dependent Insulinotropic Polypeptide (GIP) (1-39) is an endogenous 39-amino acid peptide hormone that induces insulin secretion.[1] It has been found in the upper intestines of pigs. GIP (1-39) (100 nM) enhances glucose-induced increases in insulin release in primary rat pancreatic β-cells to a greater extent than GIP (1-42).
References:
[1].Xie, L., Lu, J., Östenson, C.-G., et al.GIP1-39, a novel insulinotropic peptide form and aspects on its mechanism of actionRegul. Pept.121(1-3)107-112(2004).