Research Analysis · Everyday foundations
DPP prevention effects persisted for 15 years—without an overall microvascular difference
Among adults at high risk for type 2 diabetes, the DPP lifestyle and metformin groups still had lower cumulative diabetes incidence after 15 years. The randomized groups did not differ significantly in the study’s aggregate microvascular outcome.
By Lois Rune
Published August 26, 2026 · Updated August 26, 2026 · AI-assistance disclosure
Evidence scope
Human diabetes incidence and microvascular outcomes · long randomized follow-up
Durable diabetes prevention, but no overall microvascular difference
The prevention signal persisted after the original trial ended: compared with placebo, diabetes incidence remained lower in both intervention groups. That did not translate into a statistically significant difference among randomized groups for the combined microvascular measure.
What the 15-year follow-up found
The Diabetes Prevention Program enrolled adults at high risk for type 2 diabetes and randomized them to intensive lifestyle change, metformin or placebo. In the long-term follow-up, cumulative diabetes incidence was 55% in the lifestyle group, 56% in the metformin group and 62% in the placebo group. Relative to placebo, hazard ratios were 0.73 for lifestyle and 0.82 for metformin.
What the microvascular result means
Aggregate microvascular prevalence was 11.3% after lifestyle, 13.0% after metformin and 12.4% after placebo. Those randomized-group differences were not statistically significant. A lower prevalence among participants who had not developed diabetes is an important association within the cohort, not proof that either original assignment prevented microvascular disease.
Limits and later context
Treatment differences narrowed after the masked DPP phase, participation in follow-up selected surviving volunteers, and the 15-year paper was not a mortality trial. Later DPPOS reports did not find reductions in major cardiovascular events or mortality from the original assignments.
Safety, Funding and conflicts
Metformin can cause gastrointestinal effects and requires clinical attention to contraindications and monitoring; the lifestyle program was supervised and cannot be reduced to a generic prescription. DPP/DPPOS was funded primarily by the National Institute of Diabetes and Digestive and Kidney Diseases. The 15-year paper reported no conflicts of interest.
Sources and editorial method
Evidence review was completed separately from prose drafting across three documented passes. Primary identifiers, trial status, corrections, funding, conflicts, limitations and later context were checked before publication. See the governed issue record.
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Publication history
Published August 26, 2026 after three research passes, claim-level evidence review, editorial review and deterministic source checks. No correction or retraction affecting the central result was identified at publication.