CATEGORY: METABOLIC & BLOOD SUGAR
Just 1.3% of adults with prediabetes went on to develop type 2 diabetes over roughly three years while taking weekly tirzepatide, against 13.3% of similar adults given a placebo. That works out to about a 93% lower risk, from a large randomized trial.1 Prediabetes means blood sugar higher than normal but not yet in the diabetes range.
A Once-Weekly Shot That Imitates Two Gut Hormones
Tirzepatide is a prescription medication given as a once-weekly injection. It mimics two natural gut hormones, the chemical messengers your body releases after eating that help control appetite and blood sugar. The trial, SURMOUNT-1, enrolled adults with obesity or with overweight plus a weight-related condition. This report covers the 1,032 of them who also had prediabetes at the start. That group matters because prediabetes is both common and consequential: a meaningful share of people who have it go on to type 2 diabetes, a leading driver of heart disease, kidney disease and vision loss.
176 Weeks of Blood Tests
Three tirzepatide doses and a placebo were handed out at random, and neither participants nor their doctors knew who was receiving which. Everyone also got general healthy-eating and physical-activity counseling. The tracking then ran 176 weeks, nearly three and a half years, with regular blood tests. Those tests are how new cases of type 2 diabetes were identified. Because nothing about who received what was left to preference, the trial could measure the medication’s effect directly.1
Seventeen Weeks Off the Drug Gave Some of It Back
People on the medication also lost considerably more weight, roughly 12% to 20% of body weight depending on dose, against about 1% with placebo. Then the trial took everyone off treatment for 17 weeks. Some of the benefit eroded. Diabetes had developed in 2.4% of the medication group by that point, up from 1.3%, and some weight came back, a sign the medication manages these conditions while it is being taken rather than curing them. The placebo group stood at 13.7%.1
Digestive Side Effects, and Eli Lilly’s Role
Side effects were mostly digestive, nausea and diarrhea and constipation, usually mild to moderate and clustered in the early weeks while doses were climbing. Eli Lilly, which makes tirzepatide, funded the work. The findings describe adults with prediabetes plus obesity or overweight, not everyone whose blood sugar runs a little high. Related drugs have been put through the same kind of test. A 2024 review pooling eight randomized trials of GLP-1 drugs, which act on one of the same gut hormones, in adults with prediabetes and excess weight found far fewer progressions to type 2 diabetes on the drugs than on placebo, and many more returns to normal blood sugar. The reviewers flagged side effects there as a meaningful drawback.2
Key Takeaways
- Across 176 weeks of treatment, 1.3% of adults with prediabetes and obesity or overweight taking weekly tirzepatide developed type 2 diabetes, against 13.3% on placebo, a 93% lower risk.
- Weight loss on the medication ran roughly 12% to 20% of body weight, compared with about 1% on placebo.
- Stopping treatment for 17 weeks brought some diabetes cases and some weight back, so the benefit appears tied to continued use.
- Side effects were mostly digestive. Funding came from the company that makes tirzepatide.
References
- 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. link
- Yanto TA, Vatvani AD, Hariyanto TI, et al. Glucagon-like peptide-1 receptor agonist and new-onset diabetes in overweight/obese individuals with prediabetes: a systematic review and meta-analysis of randomized trials. Diabetes & Metabolic Syndrome: Clinical Research & Reviews. 2024;18(6):103069. link.