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Metformin

Mixed evidenceUpdated November 1, 2026 · 7 sources · Written by the AumniVIDA team

What is metformin?

Metformin is a cheap, widely used prescription drug for type 2 diabetes that lowers blood sugar mainly by reducing glucose made by the liver. Some people without diabetes take it off-label hoping to slow aging, based on animal studies and on cohort data in people with diabetes. No trial has shown it slows aging in healthy people.

Listed here because well-known people have tried it on themselves. Trying something is not recommending it; each entry says whether the person tells others to do it.

Who has tried it

Tried by 5 people we can source: 2 kept, 1 testing, 2 stopped.

Kept

Testing

Stopped

What the evidence shows

Mixed evidence

Metformin has strong evidence in type 2 diabetes. In UKPDS, overweight people with new diabetes who were given metformin had fewer diabetes complications and 36% lower all-cause mortality than those on diet alone over about 10 years [1]. That is a result in diabetes, not in healthy people.

The longevity idea grew from a 2014 UK cohort in which people with diabetes who started metformin lived slightly longer than matched people without diabetes [2], and a 2017 meta-analysis of observational studies pointed the same way [3]. A 2022 Danish study using national registers and twins found the opposite: people starting metformin for diabetes had higher mortality than people without diabetes [4]. Observational data like these cannot separate the drug from who gets it.

Two trials in older adults found a cost. Metformin blunted the gains in insulin sensitivity and fitness from aerobic training [5] and the gains in muscle from strength training [6]. TAME, a proposed trial designed to test whether metformin delays age-related disease in about 3,000 older adults, has not reported results [7]. Whether metformin slows aging in people without diabetes is unknown.

Safety

  • Metformin is FDA approved for type 2 diabetes. Taking it to slow aging without diabetes is off-label and unproven.
  • Stomach upset, diarrhea and nausea are common, especially at first. Long-term use can lower vitamin B12.
  • Lactic acidosis is rare but serious. The risk rises with poor kidney function, heavy alcohol use, severe illness and some contrast scans.
  • In two trials of older adults it reduced the benefits of exercise for fitness and muscle, which matters for anyone who trains.
  • It needs a prescription and kidney monitoring, so any use belongs with a physician.

Common questions

Does Bryan Johnson take metformin?

Yes, as of October 2026 his published protocol lists 500 mg in 6-week on and off cycles, which he describes as an experiment rather than a recommendation.

Does Peter Attia take metformin?

No. He took it for about 9 years and stopped in 2019, citing new data, including trials showing that it blunts exercise gains [5] [6]. By 2026 he no longer saw it as protective against aging in metabolically healthy people.

Does David Sinclair take metformin?

Yes. As of April 2026 he takes 1 g a day, alternating with berberine, and skips it on days he works out.

Does metformin make you live longer?

Not shown. One cohort found people with diabetes on metformin outlived matched people without diabetes [2], but a larger Danish analysis found the reverse [4]. No trial has tested lifespan in people without diabetes.

Does metformin interfere with exercise?

In two randomized trials of older adults, metformin reduced the gains in fitness and insulin sensitivity from aerobic training [5] and the muscle gained from strength training [6].

What is the TAME trial?

Targeting Aging with Metformin is a proposed trial designed to test whether metformin delays heart disease, cancer, dementia and death in older adults [7]. It has not reported results, and funding has long been a hurdle.

Sources

  1. 1.UK Prospective Diabetes Study Group. Effect of intensive blood-glucose control with metformin on complications in overweight patients with type 2 diabetes (UKPDS 34). UK Prospective Diabetes Study (UKPDS) Group. Lancet, 1998. PubMed 9742977
  2. 2.Bannister CA, Holden SE, Jenkins-Jones S, et al. Can people with type 2 diabetes live longer than those without? A comparison of mortality in people initiated with metformin or sulphonylurea monotherapy and matched, non-diabetic controls. Diabetes Obes Metab, 2014. doi:10.1111/dom.12354
  3. 3.Campbell JM, Bellman SM, Stephenson MD, Lisy K. Metformin reduces all-cause mortality and diseases of ageing independent of its effect on diabetes control: A systematic review and meta-analysis. Ageing Res Rev, 2017. doi:10.1016/j.arr.2017.08.003
  4. 4.Keys MT, Thinggaard M, Larsen LA, et al. Reassessing the evidence of a survival advantage in Type 2 diabetes treated with metformin compared with controls without diabetes: a retrospective cohort study. Int J Epidemiol, 2022. doi:10.1093/ije/dyac200
  5. 5.Konopka AR, Laurin JL, Schoenberg HM, et al. Metformin inhibits mitochondrial adaptations to aerobic exercise training in older adults. Aging Cell, 2019. doi:10.1111/acel.12880
  6. 6.Walton RG, Dungan CM, Long DE, et al. Metformin blunts muscle hypertrophy in response to progressive resistance exercise training in older adults: A randomized, double-blind, placebo-controlled, multicenter trial: The MASTERS trial. Aging Cell, 2019. doi:10.1111/acel.13039
  7. 7.Barzilai N, Crandall JP, Kritchevsky SB, et al. Metformin as a Tool to Target Aging. Cell Metab, 2016. doi:10.1016/j.cmet.2016.05.011

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