Evidence explainerMetabolic Health & Blood Sugar

Prediabetes: Lifestyle Change Beat Metformin in the Landmark Trial. Here Are the Numbers

In the Diabetes Prevention Program, a lifestyle program cut new type 2 diabetes by 58% and metformin by 31% over about 3 years. Fifteen years later both groups still had less diabetes than placebo.

By Kymata Health editorial teamPublished October 10, 2026Last verified October 10, 2026

Medical review pending. Written by our editorial team from the studies and documents cited below; a credentialed clinician has not reviewed it yet. Educational only, not medical advice.

Key takeaways

  • 3,234 adults with elevated fasting and post-load glucose (mean age 51, mean BMI 34) were randomized to placebo, metformin 850 mg twice daily, or a lifestyle program [1].
  • Diabetes incidence was 11.0, 7.8 and 4.8 cases per 100 person-years with placebo, metformin and lifestyle: a 58% reduction for lifestyle and 31% for metformin [1].
  • The lifestyle goals were at least 7% weight loss and at least 150 minutes of physical activity per week [1].
  • Over 15 years (2,776 people followed), diabetes incidence was 27% lower with lifestyle and 18% lower with metformin than placebo [2].

The Diabetes Prevention Program

The trial enrolled 3,234 people without diabetes but with elevated fasting and post-load glucose; 68% were women and 45% were from minority groups [1]. Average follow-up was 2.8 years [1].

Lifestyle reduced diabetes incidence by 58% (95% CI 48 to 66%) and metformin by 31% vs placebo, and lifestyle was significantly more effective than metformin [1].

Fifteen years later

After the trial everyone was offered lifestyle training, and 88% of survivors were followed in the Outcomes Study [2]. Over a mean 15 years, diabetes incidence stayed 27% lower in the original lifestyle group and 18% lower in the metformin group, with the differences shrinking over time [2].

What it means for you

The program behind the 58% figure was structured and coached, with a weight-loss target and weekly activity goal [1]. Metformin also worked, by less [1]. Which fits you is a conversation with your clinician.

If weight is part of the picture, our GLP-1 hub covers prescription options. Supplements marketed for blood sugar have far weaker data; psyllium, for example, showed no significant glucose lowering in people with normal glucose [3]. See our supplement guide.

Quick answers

Is metformin approved for prediabetes?

The trial tested metformin 850 mg twice daily in people with elevated glucose [1]. Whether it suits you depends on your risk and should be decided with your clinician.

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References

  1. [1]Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med, 2002. PMID 11832527
  2. [2]Long-term effects of lifestyle intervention or metformin on diabetes development and microvascular complications over 15-year follow-up: the Diabetes Prevention Program Outcomes Study. Lancet Diabetes Endocrinol, 2015. PMID 26377054
  3. [3]Psyllium fiber improves glycemic control proportional to loss of glycemic control: a meta-analysis of data in euglycemic subjects, patients at risk of type 2 diabetes mellitus, and patients being treated for type 2 diabetes mellitus. Am J Clin Nutr, 2015. PMID 26561625

Dietary supplements are not intended to diagnose, treat, cure or prevent any disease, and these statements have not been evaluated by the FDA. Prescription options need a licensed clinician. Talk to your clinician or pharmacist before starting anything new, especially if you take prescription medicines, are pregnant or breastfeeding.

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