GIP is really an incretin which is secreted in the proximal compact intestine from the presence of nutrients in the gut. GIP was initial named gastric inhibitory peptide as it was thought to lower gastric acid secretion; having said that, afterwards reports demonstrated that its principal result is stimulating insulin https://docs.google.com/presentation/d/1rm7SvzC4xKC7yajbJdfNyYionunQ34sOKyb0y1K-xhs/edit?usp=sharing