The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
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Can Type 1 Diabetics Take Wegovy for Weight Loss?
Type 1 diabetics wanting to lose weight face a specific challenge: most weight loss injections available in the UK are not routinely prescribed for type 1 diabetes. Wegovy (semaglutide) is licensed for weight management but is typically prescribed for type 2 diabetes or non-diabetic adults. If you have type 1 diabetes and are overweight, your GP will need to assess whether a weekly weight loss injection like Wegovy or Mounjaro might be suitable for your individual circumstances. This guide explains the key differences and what to expect.
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Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
Wegovy vs Mounjaro for Type 1 Diabetes: Key Differences
Wegovy (semaglutide) is a once-weekly GLP-1 receptor agonist approved in the UK for weight management in adults with a BMI of 30 or above, or 27 or above with weight-related health conditions. However, it is not specifically licensed for type 1 diabetes weight loss. In STEP clinical trials, Wegovy helped participants lose an average of approximately 15% body weight, though individual results vary significantly.
- Mechanism: GLP-1 activation only
- Dose range: 0.25 mg to 2.4 mg once weekly
- Average weight loss: ~15% body weight in trials
- Typically used alongside reduced-calorie diet and increased physical activity
Mounjaro (tirzepatide) offers a different mechanism using dual GIP and GLP-1 activation, potentially offering greater appetite suppression. SURMOUNT trials showed average weight loss of 15–21% depending on dose. Like Wegovy, Mounjaro requires a prescription and clinical assessment.
- Mechanism: Dual GIP + GLP-1 agonist
- Dose range: 2.5 mg to 15 mg once weekly
- Average weight loss: ~15–21% body weight in trials
- Requires individual prescriber assessment for type 1 suitability
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How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
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Type 1 Diabetes and Weight Loss Medication: What Your GP Needs to Consider
If you have type 1 diabetes and want to explore weight loss medication, your GP or diabetes specialist must assess whether Wegovy or Mounjaro is appropriate for you personally. Type 1 diabetics taking insulin may need careful dose adjustment if prescribed GLP-1 medication, as these medicines can affect how quickly insulin is absorbed. Your prescriber will review your blood sugar control, current medications, and overall health before making a recommendation.
Use our free GLP-1 weight loss calculator to understand projected weight loss ranges at different doses, though any actual prescription requires a full clinical assessment. Your GP may refer you to a specialist weight management service or diabetes clinic for personalised guidance. Both Wegovy and Mounjaro are prescription-only medicines — they cannot be started without professional medical evaluation.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Is Wegovy licensed for type 1 diabetes weight loss in the UK?
Wegovy is not specifically licensed for type 1 diabetes. It is approved for weight management in adults with a BMI of 30 or above, or 27 or above with weight-related conditions. If you have type 1 diabetes, your GP must assess individual suitability before any prescription, as GLP-1 medicines can interact with insulin therapy.
What's the main difference between Wegovy and Mounjaro for weight loss?
Wegovy uses a single GLP-1 mechanism; Mounjaro uses a dual GIP + GLP-1 mechanism. In clinical trials, Mounjaro showed slightly higher average weight loss (15–21%) compared to Wegovy (~15%), but individual results vary. Both require prescription and clinical assessment.
Can I take a weekly weight loss injection if I use insulin for type 1 diabetes?
It depends on your individual circumstances. GLP-1 medicines can slow stomach emptying and affect insulin absorption, potentially requiring insulin dose adjustments. Your diabetes specialist must assess safety and manage any changes to your insulin regimen carefully.
Where can I get Wegovy or Mounjaro prescribed in the UK with type 1 diabetes?
Access is through your GP or a specialist weight management service. Your GP can refer you to tier 3 specialist services, or you can seek private prescription through a UK-licensed prescriber following an online assessment. NHS availability varies by region.
Will a semaglutide weight loss injection affect my blood sugar control?
GLP-1 medicines improve blood sugar control in type 2 diabetes, but effects in type 1 diabetes are different. Because type 1 diabetics don't produce their own insulin, GLP-1 therapy alone cannot replace insulin. Your prescriber must carefully monitor blood sugars and adjust insulin doses if needed.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.