Semaglutide and tirzepatide restored normal blood sugar in most people with prediabetes and obesity. In the STEP trials, between 84.1 and 89.8 percent of people on semaglutide had normal blood sugar after 68 weeks. In the three-year SURMOUNT-1 trial, type 2 diabetes was diagnosed in 1.3 percent of people on tirzepatide and 13.3 percent on placebo. Below we collect these results and a comparison of the two molecules.
What is prediabetes?
Prediabetes is a blood sugar level that is higher than normal but still too low for a diagnosis of diabetes. SURMOUNT-5 used limits based on fasting laboratory results. These were fasting glucose of 100 to 125 mg/dl or glycated haemoglobin of 5.7 to 6.4 percent.
Normal blood sugar, or normoglycaemia, meant in this trial glycated haemoglobin below 5.7 percent and fasting glucose below 100 mg/dl. Prediabetes often occurs together with obesity. That is why trials of obesity medicines also check what happens to blood sugar.
How to check whether you have prediabetes?
Two simple blood tests are enough: fasting glucose and glycated haemoglobin. Both are done in an ordinary laboratory, and the result is compared with the limits given above. Glycated haemoglobin shows average blood sugar over several months, so it does not depend on a single meal.
It is worth repeating these tests every few months, also during treatment. In the trials it was exactly these two results that decided whether blood sugar was considered normal. How to track such measurements together with body weight and waist size is described in the guide on how to measure peptide results.
What happens without treatment?
The placebo group in the three-year SURMOUNT-1 shows this best. Participants in this group received placebo instead of the medicine the whole time. Over 176 weeks type 2 diabetes was diagnosed in 13.3 percent of them, roughly one person in eight.
Body weight in this group fell by only 1.3 percent after three years. In the STEP trials, between 47.8 and 70.4 percent of people on placebo had normal blood sugar after 68 weeks. Lifestyle changes alone therefore worked for some people, but the medicines clearly increased that share.
What did the STEP trials with semaglutide show?
An analysis of three STEP trials included 3375 adults with overweight or obesity, among them 1536 people with prediabetes. All received semaglutide 2.4 mg or placebo for 68 weeks, together with diet and exercise. The results were published in 2022 in Diabetes Care.
| Normal blood sugar after 68 weeks | Semaglutide 2.4 mg | Placebo |
|---|---|---|
| STEP 1 | 84.1 percent of people | 47.8 percent of people |
| STEP 3 | 89.5 percent of people | 55.0 percent of people |
| STEP 4 | 89.8 percent of people | 70.4 percent of people |
Semaglutide also protected people who started with normal blood sugar. In STEP 1, prediabetes appeared in 2.9 percent of them on semaglutide and 10.9 percent on placebo. Insulin sensitivity, measured with the HOMA-IR index, also improved.
What did the three-year SURMOUNT-1 trial show?
SURMOUNT-1 is the longest trial of tirzepatide in people with prediabetes. It included 1032 people with obesity and prediabetes, treated for 176 weeks, which is more than three years. The results were published in 2025 in the New England Journal of Medicine.
| SURMOUNT-1, after 176 weeks | 5 mg | 10 mg | 15 mg | Placebo |
|---|---|---|---|---|
| Weight loss | 12.3 percent | 18.7 percent | 19.7 percent | 1.3 percent |
Type 2 diabetes was diagnosed in 1.3 percent of people on tirzepatide and 13.3 percent on placebo. The risk of developing it was therefore 93 percent lower. After 17 weeks without treatment, 2.4 percent of people from the tirzepatide groups and 13.7 percent from the placebo group had diabetes.
The protection therefore partly lasted even after stopping, though part of the advantage shrank. Stomach complaints appeared mainly in the first 20 weeks, during the dose increase.
How did the predicted risk of heart disease change?
A separate analysis of the same people calculated the predicted 10-year risk of heart disease and diabetes. On tirzepatide, the predicted risk of atherosclerotic heart disease fell by 4.6 to 9.2 percent, depending on the dose. On placebo it rose by 57.9 percent over the same time.
The predicted 10-year risk of diabetes fell on tirzepatide by 17.0 to 19.6 points. On placebo it fell by 4.3 points. These are calculations from recognised risk calculators, not events observed in the trial.
Semaglutide or tirzepatide for prediabetes?
In the direct comparison SURMOUNT-5, tirzepatide restored normal blood sugar more often than semaglutide. An analysis of 425 people with prediabetes was published in April 2026. Both molecules were given at the highest tolerated dose for 72 weeks.
| SURMOUNT-5, after 72 weeks | Tirzepatide 10 or 15 mg | Semaglutide 1.7 or 2.4 mg |
|---|---|---|
| Normal blood sugar | 89.9 percent of people | 76.2 percent of people |
| Fall in HbA1c | 0.60 points | 0.48 points |
| Weight loss | 21.5 percent | 14.5 percent |
Tirzepatide also improved fasting insulin and insulin sensitivity more. At the start, average glycated haemoglobin was 5.86 percent and average BMI 40. Participants were on average 47 years old, and 63 percent were women.
What does a meta-analysis of all trials say?
A meta-analysis of eight trials with 14,564 participants, published in January 2026, confirmed this direction. GLP-1 medicines restored normal blood sugar more than four times as often as placebo. For semaglutide the odds ratio was 4.87.
All participants in these trials had obesity. The authors note that data on people with prediabetes and normal weight are missing. They rated the quality of evidence as low, mainly because of large differences between the trials.
Where to buy semaglutide and tirzepatide?
The shop offers semaglutide 3 mg Bio-Peptide for 90 EUR, in stock. Tirzepatide is available as 20 mg Bio-Peptide for 200 EUR in stock, 20 mg Genheal for 200 EUR on backorder and 40 mg Nouveaux in a pen for 350 EUR in stock.
The products in the shop are material for laboratory research, not the medicines Wegovy or Mounjaro. Diagnosis and treatment of blood sugar disorders are managed by a doctor. Results in diagnosed diabetes are described in the guides on semaglutide and the SUSTAIN trials and on tirzepatide and the SURPASS trials.
Frequently asked questions
Does semaglutide reverse prediabetes?
In the STEP trials, between 84.1 and 89.8 percent of people on semaglutide had normal blood sugar after 68 weeks, against 47.8 to 70.4 percent on placebo.
Does tirzepatide protect against diabetes?
In the three-year SURMOUNT-1, diabetes was diagnosed in 1.3 percent of people on tirzepatide and 13.3 percent on placebo, so the risk was 93 percent lower.
Which medicine works better for prediabetes?
In SURMOUNT-5, 89.9 percent of people on tirzepatide and 76.2 percent on semaglutide had normal blood sugar after 72 weeks.
Does the effect last after stopping?
After 17 weeks without tirzepatide, 2.4 percent of people from the treated groups and 13.7 percent from the placebo group had diabetes, so the protection partly lasted.
Do these results apply to people with normal weight?
No, all trial participants had overweight or obesity. Data on people with normal weight are missing.
Sources
- Perreault L, Davies M, Frias JP et al. Changes in Glucose Metabolism and Glycemic Status With Once-Weekly Subcutaneous Semaglutide 2.4 mg Among Participants With Prediabetes in the STEP Program. Diabetes Care, 2022, 45(10): 2396-2405. https://doi.org/10.2337/dc21-1785
- Jastreboff AM, le Roux CW, Stefanski A et al. Tirzepatide for Obesity Treatment and Diabetes Prevention. New England Journal of Medicine, 2025, 392(10): 958-971. https://doi.org/10.1056/NEJMoa2410819
- Hankosky ER, Lebrec J, Lee CJ et al. Tirzepatide and the 10-year predicted risk of cardiovascular disease and type 2 diabetes in adults with obesity and prediabetes: A post hoc analysis from the three-year SURMOUNT-1 trial. Diabetes, Obesity and Metabolism, 2025, 27(12): 7385-7394. https://doi.org/10.1111/dom.70143
- Galindo RJ, Aronne LJ, Horn DB et al. Reversion to normoglycemia with tirzepatide vs semaglutide in participants with obesity and prediabetes: a post hoc analysis of SURMOUNT-5. Journal of Endocrinological Investigation, 2026, 49(7): 1611-1620. https://doi.org/10.1007/s40618-026-02895-3
- Tsironikos GI, Tsolaki V, Zakynthinos G et al. Effectiveness of GLP-1 RAs in Restoring Normoglycemia in Patients With Prediabetes: An Updated Systematic Review and Meta-Analysis. Diabetes/Metabolism Research and Reviews, 2026, 42(1): e70114. https://doi.org/10.1002/dmrr.70114