Tirzepatide weight loss with type 2 diabetes is substantial on average, although it is smaller than in people without diabetes. In the SURMOUNT-2 trial, adults with obesity or overweight and type 2 diabetes lost an average of 12.8% of their body weight on tirzepatide 10 mg and 14.7% on 15 mg over 72 weeks, compared with 3.2% on placebo. In SURMOUNT-1, which excluded people with diabetes, the same two doses produced average losses of 19.5% and 20.9%.
The gap is a consistent finding in obesity medicine, and a 2025 analysis of SURMOUNT-2 suggests that blood sugar at the start of treatment explains a large part of it.
Key Takeaways
- In SURMOUNT-2, 938 adults with type 2 diabetes and a BMI of 27 or higher lost an average of 12.8% (10 mg) and 14.7% (15 mg) of body weight at 72 weeks, compared with 3.2% on placebo.
- In SURMOUNT-1, adults without diabetes lost an average of 15.0%, 19.5% and 20.9% on 5, 10 and 15 mg over the same 72 weeks, compared with 3.1% on placebo.
- A 2025 post hoc analysis of SURMOUNT-2 found that placebo corrected weight loss on 15 mg ranged from 17.7% in people starting with HbA1c below 7% to 9.0% in people starting at 9% or higher.
- The 17.7% figure in the lowest HbA1c group was broadly in line with the 17.8% placebo corrected difference reported in SURMOUNT-1 for people without diabetes.
- Proposed reasons for smaller weight loss in type 2 diabetes include reduced loss of glucose calories in urine as blood sugar improves, older age, other medications and insulin resistance.
How much weight do people with type 2 diabetes lose on tirzepatide?
People with type 2 diabetes in SURMOUNT-2 lost about 13% to 15% of their body weight on average after 72 weeks of tirzepatide. The trial, published in The Lancet by Garvey and colleagues, randomized 938 adults in seven countries to once weekly tirzepatide 10 mg (n=312), 15 mg (n=311) or placebo (n=315), alongside diet and activity counseling. Participants had a BMI of 27 or higher and an HbA1c between 7% and 10%; at baseline the average participant was 54.2 years old, weighed 100.7 kg and had an HbA1c of 8.02%.
At week 72, average weight change was -12.8% on 10 mg, -14.7% on 15 mg and -3.2% on placebo, which works out to placebo adjusted differences of -9.6 and -11.6 percentage points. Gastrointestinal effects such as nausea, diarrhea and vomiting were the most common side effects and were mostly mild to moderate, while fewer than 5% of participants stopped treatment because of adverse events.
Figure 1
Average weight change at 72 weeks, with and without type 2 diabetes
Source: Jastreboff et al., NEJM 2022 (SURMOUNT-1); Garvey et al., Lancet 2023 (SURMOUNT-2). Individual results vary.
Why do people with type 2 diabetes lose less weight on tirzepatide?
People with type 2 diabetes tend to lose less weight on almost every obesity treatment, and researchers have proposed several overlapping explanations. In a 2025 Diabetes Care analysis, Sattar and colleagues noted that weight management interventions tend to be less effective in type 2 diabetes, a pattern seen with both semaglutide and tirzepatide.
Less glucose lost in urine. When blood sugar runs high, the kidneys spill glucose, and the calories it carries, into the urine, so as treatment brings glucose down the body keeps calories it was previously losing, which can partly offset weight loss.
Age, medications and insulin. Participants with type 2 diabetes tend to be older, some glucose lowering treatments are associated with weight gain, and insulin resistance with high circulating insulin favors energy storage.
Does starting blood sugar change how much weight you lose?
People in SURMOUNT-2 who started with lower HbA1c lost noticeably more weight on tirzepatide than people who started higher. The 2025 post hoc analysis grouped participants by baseline HbA1c into four bands: below 7% (n=75), 7% to below 8% (n=417), 8% to below 9% (n=300), and 9% or higher (n=146).
Figure 2
SURMOUNT-2 participants grouped by starting HbA1c
Source: Sattar et al., Diabetes Care 2025, post hoc analysis of SURMOUNT-2 (doi:10.2337/dc25-1442).
Placebo corrected weight loss on tirzepatide 15 mg fell step by step as starting HbA1c rose, from -17.7% in the lowest band to -13.6%, -11.0% and finally -9.0% in the highest, and the 10 mg dose showed a similar pattern. The authors noted that the 17.7% result in the lowest band was broadly in line with the 17.8% placebo corrected difference in SURMOUNT-1. In other words, people with fairly well controlled type 2 diabetes responded much like people without diabetes.
Figure 3
Placebo corrected weight loss on tirzepatide 15 mg at 72 weeks, by starting HbA1c
Source: Sattar et al., Diabetes Care 2025 (post hoc analysis of SURMOUNT-2). Groups were not randomized.
The same gradient appeared for larger milestones, because the predicted proportion reaching at least 15% weight loss on 15 mg was 70% in the lowest HbA1c band and 38% in the highest.
Figure 4
Predicted share reaching at least 15% weight loss on tirzepatide 15 mg, by starting HbA1c
Source: Sattar et al., Diabetes Care 2025 (doi:10.2337/dc25-1442).
These findings come from a post hoc analysis with groups that were not randomized, the lowest HbA1c group was small, and the authors note that concurrent medications and insulin resistance may also contribute.
Why might higher blood sugar mean less weight loss?
The leading explanation is energy conservation as glucose falls. Tirzepatide lowered HbA1c in every baseline group in the SURMOUNT-2 analysis, with the largest reductions in people who started highest, who were also losing the most glucose calories in urine before treatment; correcting that hyperglycemia stops the loss, which the authors suggest would tend to offset weight reduction.
The authors also suggest tirzepatide may lead to greater weight loss in people with relatively good glycemic control, which could include people earlier in the course of type 2 diabetes. That idea comes from a post hoc analysis and has not been tested as a treatment strategy.
Does weight loss explain tirzepatide's effect on blood sugar?
Weight loss explains only part of tirzepatide's effect on blood sugar. A 2025 mediation analysis of the SURPASS trials by Vilsbøll and colleagues estimated that, compared with placebo, 12% to 27% of the HbA1c effect ran through weight loss when tirzepatide was used alone (SURPASS-1), and 25% to 45% when it was added to insulin with or without metformin (SURPASS-5). Blood sugar can therefore improve meaningfully even when the scale moves slowly. Our guide to tirzepatide and A1c covers the glucose side in more detail.
How does tirzepatide compare with semaglutide in type 2 diabetes?
In the SURPASS-2 trial, tirzepatide lowered both HbA1c and body weight more than semaglutide 1 mg in people with type 2 diabetes. The open label trial, published by Frías and colleagues in the New England Journal of Medicine, randomized 1879 adults with an average starting HbA1c of 8.28% to tirzepatide 5, 10 or 15 mg or semaglutide 1 mg for 40 weeks. Tirzepatide produced additional weight reductions of 1.9 kg, 3.6 kg and 5.5 kg compared with semaglutide across the three doses.
Figure 5
HbA1c reduction at 40 weeks in SURPASS-2, in percentage points
Source: Frías et al., NEJM 2021 (SURPASS-2).
SURPASS-2 used the 1 mg diabetes dose of semaglutide rather than the higher dose used for weight management, so it does not compare the two medicines at their weight loss doses.
Is low blood sugar a concern on tirzepatide with type 2 diabetes?
Low blood sugar was uncommon in SURPASS-2, where readings below 54 mg/dL were reported in 0.6%, 0.2% and 1.7% of people on tirzepatide 5, 10 and 15 mg and in 0.4% on semaglutide. Prescribers often adjust insulin or a sulfonylurea when tirzepatide starts. Our article on tirzepatide and low blood sugar explains why.
Does early weight loss predict how you will do?
Early weight loss is associated with better results, although slower starters still benefit. A post hoc analysis by Kokkinos and colleagues pooled tirzepatide treated participants from SURMOUNT-1 and SURMOUNT-2 and compared early responders, who lost 5% or more by week 8, with everyone else. Early responders went on to greater weight loss by week 72 and were more likely to have lower baseline HbA1c, yet participants who were not early responders still achieved clinically meaningful weight reduction. More on pacing is in our guide to why some people lose less weight on tirzepatide.
What do the trials suggest for people with type 2 diabetes?
In SURMOUNT-2, participants with type 2 diabetes lost about 13% to 15% on average at 72 weeks on tirzepatide 10 mg and 15 mg, which is less than in the trials without diabetes, and individual results varied widely in both directions.
- Track more than weight. HbA1c, fasting glucose, blood pressure and waist size may improve even while the scale moves slowly.
- Consider the starting point. People who begin with very high HbA1c may see a larger glucose response and a smaller weight response on average.
- Review other medications. Insulin, sulfonylureas and some other medicines affect both weight and the risk of low blood sugar.
Frequently Asked Questions
The Bottom Line
Tirzepatide produces meaningful weight loss in people with type 2 diabetes, with averages of 12.8% to 14.7% at 72 weeks in SURMOUNT-2, although that is less than the 19.5% to 20.9% seen at the same doses in people without diabetes. The newest analysis points to starting blood sugar as a major part of the explanation, because people with lower HbA1c lost weight at rates close to people without diabetes while those with the highest HbA1c lost less weight and saw the largest glucose improvements. Expectations and medication choices are best set with a licensed clinician.
Sources
- Garvey et al., The Lancet, 2023 (SURMOUNT-2), doi:10.1016/S0140-6736(23)01200-X.
- Jastreboff et al., New England Journal of Medicine, 2022 (SURMOUNT-1), doi:10.1056/NEJMoa2206038.
- Sattar et al., Diabetes Care, 2025, doi:10.2337/dc25-1442.
- Frías et al., New England Journal of Medicine, 2021 (SURPASS-2), doi:10.1056/NEJMoa2107519.
- Vilsbøll et al., Diabetes, Obesity and Metabolism, 2025, doi:10.1111/dom.16592.
- Kokkinos et al., Diabetes, Obesity and Metabolism, 2026, PubMed 42348366.
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