What is semaglutide and what does it actually do in the body?

Semaglutide is an engineered analog of glucagon-like peptide-1 (GLP-1), a hormone your intestinal cells naturally produce after eating. GLP-1 stimulates insulin secretion, suppresses glucagon, slows gastric emptying, and signals the hypothalamus to reduce appetite. Natural GLP-1 is degraded within two minutes of release. Semaglutide is designed to resist that degradation, its half-life is approximately one week, so the signal persists far longer than the body would otherwise sustain it.

GLP-1 receptors are expressed not only in the pancreas but also in cardiomyocytes (heart muscle cells), vascular smooth muscle, and endothelial cells. This anatomical distribution is not incidental, it is the mechanistic reason why GLP-1 receptor agonists produce cardiovascular effects that extend beyond glucose and weight management. The drug simultaneously improves insulin signaling, reduces appetite and caloric intake, lowers blood pressure modestly, reduces systemic inflammation, and directly activates receptors in cardiac and vascular tissue. That combination of mechanisms is what makes the cardiovascular trial results as large as they are. (Marso et al., NEJM, 2016)

Cardiologist's calibrated position, Solid (1) for the mechanism. GLP-1 receptor biology in cardiovascular tissue is well-characterized.

What to do: If you have been told semaglutide is only a weight loss drug, that framing is incomplete. It is a drug that acts on multiple systems relevant to cardiovascular health simultaneously.

For the full picture, read The Drug That Surprised Cardiologists.