When was semaglutide first used, and how did it reach weight management?

How did researchers arrive at semaglutide in the first place?

The story starts not with a drug but with a hormone. GLP-1 (glucagon-like peptide-1) is released naturally in the gut after eating. It signals fullness to the brain, prompts insulin release, and slows the rate at which the stomach empties. Scientists had understood this mechanism from the 1980s onwards, but natural GLP-1 breaks down in the bloodstream within minutes, too fast to be clinically useful as a medicine.

The breakthrough was engineering a molecule that mimicked GLP-1 but lasted long enough to matter. Novo Nordisk, the Danish pharmaceutical company, developed semaglutide as a fatty-acid-conjugated analogue of GLP-1: the modification means it binds to albumin in the blood, dramatically extending its half-life to roughly a week. That property is what makes a once-weekly injection possible at all. Early-phase human trials began around 2012, and the phase 3 SUSTAIN programme in type 2 diabetes followed from 2015 onwards. The NHS medicines page for semaglutide summarises the pharmacology for patients in plain terms.

If you're curious about what the drug actually does day to day, the full explainer on what semaglutide is used for covers both its licensed indications in detail.

When did semaglutide move from diabetes treatment to weight management?

The diabetes licence came first. Regulators in the US approved Ozempic (0.5 mg and 1 mg injectable semaglutide) in December 2017; European and UK approvals followed in 2018. This is still the only indication Ozempic carries, it has never held a weight-management licence, a point worth stressing because the two products are frequently confused in media coverage.

The pivot to weight management required a separate, larger clinical programme. The STEP trials, launched from around 2018, tested semaglutide at a higher maintenance dose of 2.4 mg weekly in adults with obesity but without diabetes. STEP 1, published in the New England Journal of Medicine in 2021, reported an average body-weight reduction of roughly 15% over 68 weeks, a result that set a new benchmark for medical weight management at the time. NICE subsequently appraised the evidence and recommended semaglutide (Wegovy) for NHS use in specialist weight-management services under specific criteria, published as TA875 in 2023. The UK MHRA granted its marketing authorisation for Wegovy in the same period.

A higher maintenance dose of 7.2 mg was later developed to close the gap with newer dual-agonist medicines; the MHRA approved the dedicated single-dose 7.2 mg pen in April 2026. You can read more about the current Wegovy injection on the Wegovy overview page.

What about oral semaglutide, is that a recent development?

Oral semaglutide for weight loss is very recent indeed. Making GLP-1 medicines work as tablets is technically difficult: the gut degrades peptide molecules before they can be absorbed. Novo Nordisk solved this by co-formulating semaglutide with an absorption enhancer called SNAC (sodium N-[8-(2-hydroxybenzoyl)amino]caprylate), which briefly raises the local pH in the stomach and allows the drug to cross the stomach lining.

An oral semaglutide tablet had already been approved for type 2 diabetes under the brand name Rybelsus (at much lower doses: 3 mg, 7 mg and 14 mg). The weight-management tablet is an entirely separate product. On 11 June 2026, the MHRA approved Wegovy tablets as the first oral GLP-1 medicine licensed for weight management in the UK, the UK was the first country in Europe to grant that approval. The phase 3 OASIS 4 trial reported an average weight loss of around 13.6% over 64 weeks versus placebo; among participants who stayed fully adherent to the regimen the figure was closer to 17%. No refrigeration is needed, which is a genuine practical difference from the injections. For a sense of what starting treatment looks like, the guide for people using Wegovy for the first time is a useful reference, and the first-day experience page covers what to expect in the opening 24 hours.

Given how recently the landscape shifted, it's understandable if reading about semaglutide feels like trying to catch up with a fast-moving story. The short version: the science is decades old; the weight-loss applications are new.

What does this history mean for people considering treatment today?

It means the evidence base for semaglutide as a weight-management medicine is solid but still accumulating. The trial data comes from well-designed phase 3 studies published in peer-reviewed journals. NICE has assessed that evidence independently and set out criteria for NHS eligibility. The medicine has been in clinical use, under active pharmacovigilance, long enough for the side-effect profile to be well characterised, primarily gastrointestinal effects like nausea and diarrhoea, typically most noticeable when starting or increasing the dose.

It also means that semaglutide exists in several forms with different licences, and the distinction matters. Ozempic and Rybelsus are for type 2 diabetes. Wegovy (injection and tablet) is licensed for weight management. A prescriber will always assess your full health picture before recommending any of them. Privately, that assessment can happen quickly: at nume, a GPhC-registered Independent Prescriber reviews every consultation personally, not through automated software. If you'd like to understand the current cost landscape for Wegovy, the Wegovy prices page sets out what private treatment typically involves in the UK. When you're ready to see whether treatment is right for you, check your eligibility with a free consultation.