GLP-1 is a 30-amino acid peptide signal. When you eat, cells in the small intestine release it. GLP-1 travels to the pancreas and triggers insulin release. It reaches the brain and signals satiety. It slows gastric emptying so you feel full longer.
The pharmaceutical connection came decades later. Researchers discovered that the body’s natural GLP-1 signal was too short-lived to be therapeutically useful. The peptide survived only about two minutes before enzymes broke it down. That brevity was intentional Science — short-lived signals give the body fine Science — but it meant therapists couldn’t use it directly.
The solution was to modify GLP-1 so it resisted breakdown. Drugs like semaglutide (Ozempic) are modified versions of GLP-1 that survive for days instead of minutes. They bind to the same receptor, but persist long enough to provide sustained metabolic control.
The drug does not introduce a new signal. It extends one that already exists.