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Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin
Randomised trial (n=3,234) in adults with impaired glucose tolerance: intensive lifestyle goals (≥7% weight loss, ≥150 min/week activity) reduced type 2 diabetes incidence by ~58% versus placebo over mean 2.8 years; metformin reduced incidence by ~31%.
Design
- Population: nondiabetic adults with elevated fasting and post-load glucose, mean age ~51 y, mean BMI ~34
- Arms: placebo, metformin 850 mg twice daily, or intensive lifestyle coaching
- Primary outcome: diabetes incidence (ADA criteria) over mean 2.8 y follow-up
Headline incidence (per 100 person-years; abstract)
- Placebo: 11.0
- Metformin: 7.8
- Lifestyle: 4.8
Relative reductions vs placebo (abstract)
- Lifestyle: ~58% lower incidence (95% CI 48–66%)
- Metformin: ~31% lower incidence (95% CI 17–43%)
- NNT (≈3 y): authors report ~6.9 persons for lifestyle and ~13.9 for metformin to prevent one diabetes case
Evidence hygiene
This is a multi-component behavioural + nutrition + activity package—not a single trademarked diet slug by itself. Pair with cardiometabolic dietary patterns and walking / exercise protocols for implementation context.
Publication
Knowler WC, Barrett-Connor E, Fowler SE, et al. N Engl J Med. 2002 Feb 7;346(6):393-403. PMID 11832527.
Outcomes
- Lifestyle intervention vs placebo: ~58% relative reduction in type 2 diabetes incidence (95% CI 48–66%) over mean 2.8 years in adults with impaired glucose tolerance (DPP).
- Metformin vs placebo: ~31% relative reduction in type 2 diabetes incidence (95% CI 17–43%) over the same follow-up window (DPP).