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Mfn4.0
Metformin Research
Mostly mechanism / observational
2,112 peer-reviewed studies
Showing the 1002 most recent of 2112 studies.
All 2110 database studies by type: RCT 1513 · Meta-Analysis 505 · Systematic Review 79 · Review 11 · Observational 1 · other 1
What the evidence says
Mostly mechanism / observational
Most Metformin studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from high-quality meta-analyses and randomised trials published 1998–2026 with a typical study size of 365 participants.
Based on 999 studies · 368 meta-analyses · 568 RCTs · 340,015 total participants
Confidence
High confidence
By outcome
Glycemic & metabolicLowers blood glucose and HbA1c and improves insulin sensitivity — the established, proven effect · Weeks · Improves insulin sensitivity; the established first-line metabolic effect (longevity/geroprotection remains contested) · Weeks
Mostly mechanism / observational306 studies
Exercise interference
Mostly mechanism / observational28 studies
Safety profile
Mostly mechanism / observational23 studies
Aging & mortalityObservational/meta-analytic data suggest lower all-cause mortality and age-related disease in diabetics — confounded, not proven causal · Years
Mostly mechanism / observational15 studies
Active research area
622 studies in the last 5 years · Latest meta-analysis: 2026
199820122026
1Meta-Analysisn=1,159 · large study2026
In plain English: Conclusions In this IPD meta-analysis, metformin was not associated with a reduction in GDM, but was associated with an increase in gestational age at delivery.
Mousa A, Løvvik TS, Carlsen SM, Belsti Y, Enticott J, Tay CT, Nikkinen H, Morin-Papunen L, Tertti K, Rönnemaa T, Rowan J, Dodd J, Deussen A, Hague WM, Zawiejska A, Arshad R, Mathews JE, Wasim T, Mohamed MA, Mohebbi M, Yefet E, Nachum Z, Ainuddin J, Refuerzo JS, Burden C, Norman JE, Syngelaki A, Nicolaides K, Shehata H, Vanky E, Teede HJ. · NEJM evidence (2026)
Results Ten trials (N=2695) met inclusion criteria and seven provided IPD (n=2485; 92.2% of available IPD).
Metformin was associated with marginally lower fasting blood glucose level (mean difference [MD], -0.06 mmol/l; 95% CI, -0.10 to -0.01), with no apparent difference in 2-hour postload blood glucose level.
Metformin was also associated with longer gestation (MD, 0.30 weeks' gestation; 95% CI, 0.06 to 0.54), lower odds of preterm birth (adjusted odds ratio, 0.64; 95% CI, 0.47 to 0.89), and larger neonatal head circumference (MD, 2.43 percentile; 95% CI, 0.13 to 4.72).