The hormone that raises blood sugar
Glucagon is a hormone made by the alpha cells of the pancreas, and its main job is the mirror image of insulin’s. When blood sugar drops — between meals or overnight — glucagon signals the liver to release stored glucose, pushing levels back up. Insulin lowers blood sugar; glucagon raises it. Working against each other, the two keep your blood sugar in a stable range.
The GLP-1 name connection
Here’s the part that trips people up: GLP-1 stands for glucagon-like peptide-1. The “glucagon-like” isn’t a coincidence — GLP-1 and glucagon are cut from the same larger precursor protein and share a similar molecular shape, which is how GLP-1 got its name. Despite that resemblance, they do different jobs: GLP-1 mainly boosts insulin and curbs appetite, while glucagon raises blood sugar. Knowing this naming quirk clears up a common point of confusion about where the “GLP-1” label even comes from.
Why glucagon is showing up in newer drugs
Glucagon is more than a naming footnote. Some investigational medications deliberately activate the glucagon receptor alongside the incretin receptors, because glucagon signaling can influence energy expenditure and how the body handles fat. That’s the idea behind the triple agonist retatrutide, which targets GLP-1, GIP, and glucagon together. It’s an area of active research rather than settled medicine, so if you see glucagon mentioned in a drug’s mechanism, treat it as a sign the molecule is doing something beyond the standard GLP-1 approach — and a good thing to ask your clinician about.