In response to Glucose ingestion, proglucagon in the intestinal L cells is cleaved into GLP-1 (1-36). Prior to secretion into the circulation, GLP-1 (1-36) is further processed into amidated GLP-1 (7-36) and small amounts of glycine-extended GLP-1 (7-37). Both GLP-1 (7-36) and GLP-1 (7-37), causes glucose dependent release of insulin by pancreatic beta-cells. They also play a role in gastric motility (gastric emptying), on the suppression of plasma glucagon levels (glucose production) and possibly on the promotion of satiety and stimulation of glucose disposal in peripheral tissues independent of the actions of insulin. GLP-1 peptides such as GLP-1 (1-36) have been used to investigate restoration of pancreatic beta cell function. GLP-1 is also produced in the central nervous system.