GLP-1; incretin; glucagon-like peptide
Glucagon-like peptide 1 belongs to a family of hormones called the incretins, so-called because they enhance the secretion of insulin. Glucagon-like peptide 1 is a product of a molecule called pre-proglucagon, a polypeptide which is split to produce many hormones, including glucagon. Because they come from the same source, these hormones share some similarities, so are called ‘glucagon-like’. Cells found in the lining of the small intestine (called L-cells) are the major source of glucagon-like peptide 1, although it is also secreted in smaller quantities by the pancreas and the central nervous system. Glucagon-like peptide 1 encourages the release of insulin from the pancreas, increases the volume of cells in the pancreas that produce insulin (beta cells) and holds back glucagon release. Glucagon-like peptide 1 also increases the feeling of fullness during and between meals by acting on appetite centres in the brain and by slowing the emptying of the stomach.
Food is the main stimulus of glucagon-like peptide 1 release, with increased hormone levels detectable after 10 minutes of starting to eat and remaining raised in the blood circulation for several hours after that. The hormone somatostatin holds back the production of glucagon-like peptide 1.
There are no known cases of too much glucagon-like peptide 1. Recently drugs have been developed to mimic glucagon-like peptide 1 in the blood circulation to improve the control of glucose levels in type-2 diabetes. Levels of glucagon-like peptide 1 are also naturally increased after some types of weight-related surgery, which is thought to contribute to the observed weight loss and improvement of type-2 diabetes in these patients.
It has been suggested that too little glucagon-like peptide 1 released after a meal may increase the likelihood of, or worsen, obesity. Since glucagon-like peptide 1 reduces appetite after a meal, if the body releases less of this hormone, individuals may eat more during a meal and are more likely to snack between meals. Dieting, or natural weight loss, is linked to a decrease in glucagon-like peptide 1. The result may be an increased appetite and tendency to regain weight. However, more research is needed to confirm this.
Last reviewed: Feb 2015