GLP-1 New Drug R&D Service: Introduction of GLP-1sbr br br Glucagon-like peptide-1 (GLP-1) is a 30- or 31-amino-acid-long peptide hormone. GLP-1 exists in two equally bioactive forms, GLP-1 (7-37) amide and GLP-1 (7-36) amide. GLP-1 is a biological product derived from the post-translational processing of proglucagon. GLP-1 is secreted by the enteroendocrine L cells, but also by some neuronal populations in the hindbrain. GLP-1 potentiates insulin release and reduces glucagon’s concentration in physiological conditions.