Glucagon-like peptide-1 (GLP-1) is an incretin derived from the transcription product of the proglucagon gene. The major source of GLP-1 in the body is the intestinal L cell that secretes GLP-1 as a gut hormone. Its physiological functions include promoting insulin sensitivity, decreasing food intake by increasing satiety in brain and increasing insulin secretion from the pancreas in a glucose-dependent manner.