Glucagon-like peptide 1 (GLP-1) is a hormone produced in the intestines. It plays an important role in managing blood sugar levels after eating. When you eat, your body needs to balance the glucose (sugar) that enters your bloodstream from the food you consumed. GLP-1 helps by prompting the release of insulin, a hormone responsible for lowering blood sugar levels. At the same time, it also slows down the release of glucagon (another hormone), which increases blood sugar levels.
Where is GLP-1 Produced?
GLP-1 is produced in the intestines, more specifically by the L-cells which are found in the ileum and colon (parts of the small and large intestines). When you eat, the food passes through the digestive system and comes into contact with these L-cells, and this “contact” triggers them to release GLP-1 into the bloodstream.
How is GLP-1 Produced?
The production of GLP-1 starts with a larger molecule called proglucagon, which is made in the L-cells and pancreatic alpha cells. However, it’s only in the L-cells where proglucagon gets processed into GLP-1. This happens through a series of steps involving specific enzymes called prohormone convertases which cut the proglucagon into smaller pieces – one of which is GLP-1.
The GLP-1 that is released by the L-cells comes in two forms: GLP-1 (7-36) amide and GLP-1 (7-37). Both forms are active, but GLP-1 (7-36) amide is more common in the body. After its release, GLP-1 doesn’t last long in the bloodstream because it is quickly broken down by an enzyme called dipeptidyl peptidase IV (DPP-IV) which then renders it inactive.
What Stimulates GLP-1 Release?
Several factors stimulate the release and important of GLP-1 from L-cells, mostly nutrients from food. They include:
Glucose and Fats
Foods rich in glucose (sugar) or fats directly stimulate the L-cells to release GLP-1. This is one of the primary ways your body ensures that insulin is available to manage the rise in blood sugar after eating.
Neural Signals
When you start eating, your brain sends signals via the vagus nerve to stimulate GLP-1 release even before the nutrients have a chance to reach the intestines.
Hormones and Neurotransmitters
Certain hormones and neurotransmitters also influence GLP-1 release. Gastrin-releasing peptide (GRP) stimulates GLP-1 secretion. Others include acetylcholine (a neurotransmitter) and leptin (a hormone involved in regulating energy balance).
What are the Main Functions of GLP-1?
GLP-1 has several important functions in the body, particularly related to blood sugar regulation and digestion:
GLP-1 enhances the release of insulin from the pancreas. Insulin helps lower blood sugar levels by promoting the uptake of glucose into cells for energy or storage.
It reduces the release of glucagon preventing the liver from producing too much glucose, which could otherwise raise blood sugar levels.
GLP-1 also slows down the emptying of food from the stomach into the intestines which help moderate the rise in blood sugar after eating and also contributes to a feeling of fullness.
Finally, GLP-1 supports the health of the pancreatic beta cells, which produce insulin and can be particularly beneficial for people with type 2 diabetes.