Mounjaro (tirzepatide) is licensed in the UK for improving blood sugar control in adults with type 2 diabetes, alongside diet and exercise, as well as for weight management. In the SURPASS-1 trial, Mounjaro reduced HbA1c by 1.87 to 2.07 percentage points compared with placebo, and 81 to 86% of participants reached an HbA1c target of 6.5% or below. In head-to-head trial data, Mounjaro also outperformed injectable semaglutide for both blood sugar control and weight loss. For the diabetes indication, treatment typically starts at 2.5mg weekly, increasing to 5mg after four weeks, since most of the glucose-lowering benefit is seen at this dose — a genuinely different pattern to the weight-management titration schedule.
Mounjaro is one of a small number of GLP-1 medicines authorised in the UK for two separate purposes: weight management in adults meeting standard BMI criteria, and improving blood sugar control in adults with type 2 diabetes whose condition isn't adequately managed by diet, exercise and existing medication alone. These are genuinely separate clinical indications, each backed by its own dedicated trial programme — SURMOUNT for weight management, and SURPASS for diabetes. Eligibility for one doesn't automatically confirm eligibility for the other, and your prescriber will assess which use applies to your specific circumstances, reviewing your full medical history during your consultation.
The SURPASS Trial Programme: What the Evidence ShowsSURPASS-1: Mounjaro vs Placebo
This 40-week trial studied 478 adults with type 2 diabetes whose blood sugar wasn't adequately controlled by diet and exercise alone, comparing Mounjaro's three doses (5mg, 10mg, 15mg) against placebo. All three doses significantly reduced HbA1c — by 1.87%, 1.89% and 2.07% respectively, compared with a slight increase (+0.04%) on placebo. Between 81% and 86% of participants taking Mounjaro reached an HbA1c target of 6.5% or below, and weight loss of 7 to 9.5kg was also observed as a secondary outcome.
SURPASS-2: Mounjaro vs Injectable Semaglutide
This head-to-head trial compared all three Mounjaro doses directly against semaglutide 1mg (the injectable diabetes dose). All three Mounjaro doses achieved superior HbA1c and weight reductions compared with semaglutide — a genuinely significant result, since semaglutide is itself a well-established and effective diabetes treatment.
Across SURPASS-1 to SURPASS-5
Taken together, the five core SURPASS trials showed consistent results: HbA1c reductions of 1.9 to 2.6 percentage points, and weight loss of 6.6% to 13.9%, over 40 to 52 weeks of treatment. Between 23% and 52% of participants achieved full glucose normalisation (HbA1c below 5.7%). Blood pressure improvements were also observed, with systolic blood pressure reductions of 2.8 to 12.6 mmHg.
Worth knowing
SURPASS-CVOT, a large cardiovascular outcomes trial involving over 13,000 participants with type 2 diabetes and established cardiovascular disease, compared Mounjaro against dulaglutide (a GLP-1 medicine already approved for cardiovascular risk reduction) over an average follow-up of around 4 years. Mounjaro met the trial's goal of demonstrating it was at least as safe as dulaglutide for cardiovascular outcomes, though it didn't demonstrate superiority in this particular comparison.
This is one of the most practically important differences to understand. For weight management, Mounjaro follows a six-step titration schedule up to a maximum of 15mg — see our dedicated Mounjaro dose schedule guide for the complete weight-management timeline. For the diabetes indication, the pattern is different: treatment is initiated at 2.5mg weekly, then increased to 5mg after four weeks — and in the SURPASS trials, the majority of the glucose-lowering effect was seen at this 5mg dose, with only modest further HbA1c improvement at higher doses.
| Weight management | Type 2 diabetes | |
|---|---|---|
| Starting dose | 2.5mg | 2.5mg |
| Early titration | Increase every 4 weeks toward 15mg | Increase to 5mg after 4 weeks |
| Where most benefit is seen | Higher doses generally drive greater weight loss | Much of the glucose-lowering benefit is seen at 5mg |
| Further increases | Common, to maximise weight loss | By 2.5mg increments, at least 4 weeks apart, if needed |
This doesn't mean higher doses have no value for diabetes management — further increments (5mg → 7.5mg → 10mg → 12.5mg → 15mg) remain available if blood sugar control isn't adequate at 5mg, always spaced at least four weeks apart to help manage gastrointestinal side effects. But it does mean the clinical decision-making is different: for diabetes, your prescriber may be satisfied with a lower maintenance dose than someone using Mounjaro primarily for weight loss.
How Mounjaro Fits With Other Diabetes TreatmentsMetformin remains the standard first-line treatment for type 2 diabetes in the UK, and Mounjaro isn't typically a first-choice replacement for most people. The SURPASS trials studied Mounjaro both as monotherapy in early diabetes and as an addition to existing treatment (including metformin and, in some trials, insulin), reflecting the range of situations where it may be appropriate. Your prescriber will consider where Mounjaro fits within your existing diabetes management plan, based on your current medicines, how well controlled your diabetes is, and your broader health picture.
Side effects for the diabetes indication are broadly consistent with those seen in weight-management use — nausea, diarrhoea, vomiting and other gastrointestinal symptoms are the most commonly reported, particularly during dose escalation, and tend to be mild to moderate; see our dedicated Mounjaro side effects guide for full management advice. Across the SURPASS trials, side effects were described as mild to moderate and transient, decreasing over time as treatment continued. Notably, no clinically significant or severe hypoglycaemia was reported in SURPASS-1, reflecting Mounjaro's glucose-dependent mechanism — though this risk increases if you're also taking insulin or a sulfonylurea, since those medicines lower blood sugar regardless of your current level.
Important
If you're taking Mounjaro for type 2 diabetes alongside insulin or a sulfonylurea, discuss hypoglycaemia risk directly with your prescriber, since your other diabetes medicines may need adjusting when starting Mounjaro. Familiarise yourself with the signs of low blood sugar — shakiness, sweating, confusion — before beginning treatment.
Beyond blood sugar control, the SURPASS trials also documented meaningful improvements in systolic blood pressure, ranging from 2.8 to 12.6 mmHg across the programme. This matters because cardiovascular risk factors often cluster together in people with type 2 diabetes, and improvements across multiple markers — not just HbA1c — contribute to the overall clinical picture your prescriber will consider when assessing how well treatment is working for you.
Monitoring Your ProgressIf you're taking Mounjaro for type 2 diabetes, regular HbA1c testing — typically every 3 to 6 months — remains the standard way to track how well your treatment is working, alongside home blood glucose monitoring if you use it. Weight, blood pressure and cholesterol are also worth tracking over time, since the SURPASS trials showed improvements across all of these alongside HbA1c. Bring this data to your regular reviews with your prescriber, who can use the full picture to decide whether your current dose remains appropriate or whether an adjustment might help. Understanding these figures gives you a realistic sense of what to expect, and a useful benchmark for judging your own progress over the coming months.
Manage Your Weight and Blood Sugar With Mounjaro
Mounjaro is available to order now through Happy Pharmacy, licensed for both weight management and improving blood sugar control in type 2 diabetes.
Start Your Free Online Consultation → Happy Pharmacy is a GPhC-registered pharmacy (No. 9012585) — Superintendent Pharmacist: Palvinder Deol — Rated 4.8★ Excellent on Trustpilot- Rosenstock J, et al. Efficacy and safety of a novel dual GIP and GLP-1 receptor agonist tirzepatide in patients with type 2 diabetes (SURPASS-1). Lancet. 2021.
- Frias JP, et al. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes (SURPASS-2). N Engl J Med. 2021.
- Eli Lilly and Company. Clinical Data for A1C and Weight Change, Mounjaro (tirzepatide), mounjaro.lilly.com/hcp.
- DiabetesOnTheNet. Factsheet: Tirzepatide for management of type 2 diabetes.
- Mounjaro® (tirzepatide) UK Summary of Product Characteristics.
- Frias JP, et al. SURPASS-CVOT: Tirzepatide vs Dulaglutide in Type 2 Diabetes and Cardiovascular Disease. Presented at ADA Scientific Sessions, 2026.