Semaglutide

Deep dive

Semaglutide: complete reference

Semaglutide is a long-acting GLP-1 receptor agonist developed by Novo Nordisk, structurally derived from native human GLP-1 with two key modifications: an alpha-aminoisobutyric acid substitution at position 8 (which resists DPP-4 degradation) and a C18 fatty diacid chain attached via a glutamic-acid spacer (which enables non-covalent binding to albumin in plasma, extending half-life to approximately 7 days). This pharmacokinetic profile enables once-weekly subcutaneous injection (Ozempic for T2D, Wegovy for chronic weight management) or once-daily oral administration (Rybelsus, formulated with the absorption enhancer SNAC). The molecule was first approved by the FDA in 2017 (Ozempic for type 2 diabetes), with Wegovy following in 2021 for weight management and Rybelsus in 2019 as the first oral GLP-1. Clinical trials have established semaglutide as one of the most effective non-surgical weight-loss medications ever approved — STEP-1 demonstrated 14.9% average body weight reduction at 68 weeks — and its cardiovascular outcomes data (SUSTAIN-6 and SELECT trials) support CV event reduction in both diabetic and non-diabetic obesity patients.

In practice

The same semaglutide molecule is in three brand-name medications: Ozempic (lower doses, for diabetes), Wegovy (higher dose, for weight), and Rybelsus (oral, for diabetes). Pharmacokinetically identical; different doses + dosing routes.

Clinical context

Semaglutide is the most-prescribed GLP-1 globally as of 2026 and serves as the comparator molecule in most head-to-head GLP-1 trials.