Semaglutide

Semaglutide isn't one drug with a secret identity — it's a single molecule sold under three different names. Ozempic and Rybelsus treat type 2 diabetes (one injected, one a daily pill); Wegovy is the exact same compound at a higher injected dose, cleared for chronic weight management. But the stranger story is where this whole class of drugs came from — and it did not begin in a Novo Nordisk lab.

The trail runs back to the early 1980s, when endocrinologist Joel Habener's team at Massachusetts General Hospital sequenced the human glucagon gene and found, tucked inside it, the blueprint for a second, unexpected hormone. A chemist in his lab, Svetlana Mojsov, synthesized the active fragment — what we now call GLP-1 — and helped show it triggered insulin only when blood sugar was already high, a built-in safety feature that would make the whole class far safer than older diabetes drugs. Around the same time, Jens Juul Holst's group in Copenhagen was independently pulling GLP-1 out of pig intestines. There was just one problem: native human GLP-1 is useless as a medicine, because the body's own enzymes chew it up in under two minutes.

The fix came from a wildly different direction — Gila monster venom. In the early 1990s, John Eng and colleagues at a Bronx VA hospital were combing through venomous-lizard saliva, drawn partly by the fact that Gila monsters eat only a handful of times a year, yet something in their biology lets them keep tight blood-sugar control between those rare, enormous meals. Eng isolated exendin-4, a peptide that flips the same switch as human GLP-1 but — thanks to a single swapped amino acid — shrugs off the enzyme that destroys the human one; when his own hospital and the VA both passed on it, he filed the patent himself, out of pocket, and licensed it to a small biotech. That became a separate drug, exenatide (Byetta), the first-ever GLP-1 medicine in 2005 — and when patients on it started dropping weight as an off-target surprise, the entire industry, Novo Nordisk included, realized this pathway was worth chasing for obesity, not just diabetes.

Semaglutide's own family tree, though, runs through the human hormone, not the lizard. Novo Nordisk had already learned to make a molecule linger by bolting on a fatty-acid tail that hitches a ride on albumin, the blood's most abundant transport protein — a trick borrowed from its long-acting insulin. Chemists Jesper Lau and Lotte Bjerre Knudsen applied it to GLP-1 itself, first building once-daily liraglutide, then stretching the chemistry into semaglutide: roughly 94% identical to native human GLP-1 and engineered to survive a full week between shots (Ozempic in 2017, Rybelsus in 2019, Wegovy in 2021). Credit for the underlying science is still an open sore — Mojsov was left off the original patents and fought for more than a decade to be named an inventor, and it wasn't until the 2025 Breakthrough Prize that all five key contributors, her included, were finally honored together.