The major source of GLP-1 in the body is the intestinal L cell that secretes GLP-1 as a gut hormone.

It is generated in the alpha cells of the pancreas and in the intestinal L cells in the distal ileum and colon.

IL-6 also appears to have systemic effects on the liver, adipose tissue and the immune system, and mediates crosstalk between intestinal L cells and pancreatic islets.

In intestinal L cells, proglucagon is cleaved to the alternate products glicentin, GLP-1 (an incretin), IP-2, and GLP-2 (promotes intestinal growth).