GLP-1 for diabetes vs weight loss: same drugs, different rules

Most questions about GLP-1 and diabetes vs weight loss come down to one confusion: the same active ingredient can be sold under two names with two sets of rules. In the UK, semaglutide is Ozempic and Rybelsus when licensed for type 2 diabetes and Wegovy when licensed for weight management, while tirzepatide (Mounjaro) and orforglipron (Foundayo) hold both licences under one name. The molecule is the same; the doses, eligibility rules and NHS route are not.

This is information only, not medical advice. Every medicine here is prescription-only in the UK; a prescriber decides whether any suits you, and for which purpose.

GLP-1 for diabetes vs weight loss: what the UK licences say

As of October 2026, the UK SmPCs (summaries of product characteristics) say:

• Ozempic (semaglutide injection) and Rybelsus (semaglutide tablets): adults with insufficiently controlled type 2 diabetes, alongside diet and exercise.
• Wegovy (semaglutide injection): weight management in adults with a BMI of 30 or more, or 27 to under 30 with a weight-related condition, and in adolescents aged 12 and over with obesity who weigh more than 60 kg; also adults with established cardiovascular disease and a BMI of 27 or more, to reduce the risk of heart attack, stroke and cardiovascular death; and, in adults, a liver condition (non-cirrhotic MASH).
• Wegovy tablets (oral semaglutide): adult weight management, same BMI rules.
• Mounjaro (tirzepatide): both. Type 2 diabetes from age 10, and adult weight management under the same BMI rules, with type 2 diabetes itself listed among the conditions that count.
• Foundayo (orforglipron): both. Adult weight management under the same BMI rules, and type 2 diabetes in adults, alone or with other diabetes medicines.

The NHS medicines pages and the MHRA's GLP-1 guidance (February 2026) draw the same lines; our comparison page sets the four medicines side by side.

Eligibility: BMI thresholds versus diabetes criteria

Weight management starts from body size: a BMI of 30 or more, or 27 to under 30 plus at least one weight-related condition. NHS funding is narrower; see who is eligible for GLP-1 treatment in the UK.

Type 2 diabetes licences contain no BMI threshold. They ask whether an adult's diabetes is insufficiently controlled, and carry limits of their own: semaglutide should not be used in type 1 diabetes and is not a substitute for insulin, and when any of them is added to insulin or a sulfonylurea the SmPCs say those doses may need reducing to limit low blood sugar.

Both at once. Under Mounjaro's weight-management licence, type 2 diabetes is a qualifying condition from a BMI of 27, so one person can meet either indication.

Dose ladders: where the SmPCs differ

• Semaglutide injection. Ozempic starts at 0.25 mg a week, rising to 0.5, 1 and a maximum of 2 mg, each step at least four weeks apart. Wegovy takes the same three steps, then 1.7 mg and a 2.4 mg maintenance dose from week 17; adults with obesity can go to 7.2 mg after at least four weeks on 2.4 mg.
• Semaglutide tablets. Rybelsus runs 1.5 mg, 4 mg and a maximum of 9 mg a day. Wegovy tablets take the same steps and continue to 25 mg, with at least a month at each level.
• Tirzepatide (Mounjaro). One ladder for both uses: 2.5 mg a week for four weeks, then 5 mg, rising in 2.5 mg steps at least four weeks apart to a maximum of 15 mg. For weight management the SmPC adds a review if less than 5% of starting weight has gone after six months on the highest tolerated dose.
• Orforglipron (Foundayo). One ladder for both uses: 0.8 mg a day for the first month, then 2.5 mg, then 5.5 mg, with optional steps to 9, 14.5 and 17.2 mg at least 30 days apart.

Full ladders: Mounjaro, Wegovy, Wegovy pill, Foundayo.

People with type 2 diabetes lose less weight in the trials

In STEP 1, adults without diabetes on Wegovy 2.4 mg lost 14.9% of body weight over 68 weeks, against 2.4% on placebo; in STEP 2, a trial of 1,210 adults with type 2 diabetes, those on the same dose lost 9.6%, against 3.4% on placebo, while HbA1c fell by 1.6 percentage points against 0.4. For tirzepatide, SURMOUNT-1 (no diabetes) recorded 21.4% at 10 mg and 22.5% at 15 mg over 72 weeks; SURMOUNT-2, a trial of 938 adults with type 2 diabetes, recorded 13.4% and 15.7%, against 3.3%.

These are averages from separate trials, not head-to-head comparisons.

NHS access: two different doors

For type 2 diabetes, the route is NICE's diabetes guideline NG28 (updated February 2026). It covers GLP-1 receptor agonists as a class and names tirzepatide alongside them. They can be considered for adults with early-onset type 2 diabetes (diagnosed before 40) who need further medicines, and for adults with type 2 diabetes living with obesity after at least three months on initial treatment. Its appraisal of tirzepatide for diabetes (TA924, 2023) still stands, and NICE is working to align the two.

For weight management, NICE recommends the Wegovy injection within specialist weight-management services for up to two years (TA875) and Mounjaro through a phased rollout that began in 2025 with a BMI of 40 or more plus at least four of five named conditions, widening to 35 to 39.9 in 2026/27 (TA1026). Since May 2026 NICE also recommends Wegovy for adults with established cardiovascular disease and a BMI of 27 or more (TA1152). Neither tablet is NHS-funded for weight loss, and these rules describe England.

Why a diabetes brand is not a shortcut to weight loss

• The licence. The MHRA says GLP-1 medicines are for people who are overweight or have diabetes, not for cosmetic weight loss, and it has not assessed them outside their licensed uses.
• Supply. During the shortages, a Department of Health and Social Care National Patient Safety Alert (July 2023, updated January 2024) said off-label use for obesity was strongly discouraged and supplies had to be conserved for people with diabetes.
• The dose. Ozempic stops at 2 mg and Rybelsus at 9 mg; the weight-management evidence was gathered at 2.4 mg and 25 mg, and the MHRA advises professional advice before switching between them.

Side effects are the same whichever brand is used: mainly nausea, diarrhoea, constipation and vomiting, with rarer risks such as pancreatitis, and more low blood sugar alongside insulin or a sulfonylurea. The Mounjaro SmPC adds that a rapid improvement in blood sugar can temporarily worsen diabetic eye disease. Report suspected side effects through the MHRA Yellow Card scheme; see also managing GLP-1 side effects.

The prescriber decides

For diabetes, weight or both, the product, dose and route (NHS or private) are clinical decisions made after a consultation. Private prices vary between regulated providers, and the MHRA warns against buying from unregulated sellers such as beauty salons or social media. See our FAQ page and GLP-1 medications compared.

Frequently asked questions

Sources

1. SmPCs (emc): Ozempic, Rybelsus, Wegovy FlexTouch, Wegovy tablets, Mounjaro KwikPen, Foundayo.
2. NHS: Semaglutide, Tirzepatide.
3. NICE: NG28, TA924, TA875, TA1026, TA1152.
4. MHRA: GLP-1 medicines: what you need to know.
5. DHSC: NatPSA/2023/008/DHSC, NatPSA/2024/001/DHSC.

Related reading

• Who is eligible for GLP-1 treatment in the UK?
• GLP-1 medications compared
• GLP-1 tablets vs injections