The world's most famous anti-ageing drug candidate: where the evidence stands.
TL;DR: Metformin is a first-line type 2 diabetes drug with decades of safety data and intriguing observational hints, but it has not been proven to slow ageing or extend healthy lifespan in people without diabetes. The TAME trial aims to answer that question, but as of 2026 it remains in planning and fundraising stages.
Metformin is a biguanide medication that lowers blood glucose primarily by reducing liver glucose production and improving insulin sensitivity. It has been used in the UK for type 2 diabetes since the 1950s and is now one of the most commonly prescribed drugs worldwide.
Its longevity interest began with observational studies suggesting that people with type 2 diabetes on metformin lived at least as long as, and sometimes longer than, people without diabetes. If a diabetes drug could match non-diabetic survival, the reasoning went, it might benefit healthy ageing in non-diabetics too.
Bannister et al. (2014) reported that metformin-treated type 2 diabetes patients in the UK Clinical Practice Research Datalink had lower all-cause mortality than matched non-diabetic controls. This study generated enormous interest, but observational data cannot prove causation. People prescribed metformin may differ in health-seeking behaviour, screening, and other unmeasured ways from controls.
None of these have shown that metformin extends lifespan or delays major age-related diseases in healthy adults.
TAME stands for Targeting Aging with Metformin. Proposed by Dr Nir Barzilai and colleagues, the trial is designed to enrol approximately 3,000 older adults aged 65–79 without diabetes and randomise them to metformin or placebo for roughly six years. The primary endpoint is a composite of major age-related diseases: cardiovascular disease, cancer, dementia and mortality.
Current status: TAME has faced repeated funding and regulatory challenges. As of 2026, the trial has not begun enrolment. The US Food and Drug Administration has engaged with the proposal, but the commercial barrier is that metformin is generic: no pharmaceutical company has a strong financial incentive to fund a multi-hundred-million-dollar longevity trial.
Researchers have proposed several ways metformin might influence ageing:
However, it is unclear whether these mechanisms produce meaningful anti-ageing effects in humans without diabetes.
Common adverse effects include:
Serious risks include:
Metformin is a prescription-only medicine (POM) in the UK. It is licensed for type 2 diabetes and polycystic ovary syndrome (PCOS), not for longevity or healthy ageing. Taking metformin for anti-ageing without medical supervision is off-label use and is not recommended.
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These sources are referenced inline throughout the article and listed below for full transparency.
"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." Influential UK observational study.
View DOI"Metformin as a Tool to Target Aging." Proposal and rationale for the TAME trial.
View DOI"The metformin-mediated changes in the aging transcriptome are tissue-specific and dependent on sex." Explores molecular effects of metformin across tissues.
View DOI"Senolytics in idiopathic pulmonary fibrosis." Included for context on alternative ageing-targeting interventions.
View DOI"Metformin and aging: a review." Summarises clinical and preclinical evidence, mechanisms and ongoing trials.
View DOINo human trial has proven that metformin extends lifespan. The TAME trial is designed to test whether metformin can delay the onset of multiple age-related diseases, not whether it increases maximum lifespan.
TAME stands for Targeting Aging with Metformin. It is a proposed multi-site randomised controlled trial led by Dr Nir Barzilai that would test whether metformin delays the time to a composite endpoint of age-related diseases in older adults without diabetes.
Some longevity enthusiasts use metformin off-label based on observational studies in people with diabetes and on animal data. This is not recommended without medical supervision because metformin can cause serious side effects and is not approved for anti-ageing.
Common side effects include diarrhoea, nausea and vitamin B12 deficiency. Rare but serious risks include lactic acidosis, especially in people with kidney or liver disease. Metformin is usually stopped before iodinated contrast scans.
The content on this site is for informational purposes only and is not medical advice. Metformin is a prescription-only medicine in the UK and should only be used under medical supervision for licensed indications. Do not use metformin for longevity or anti-ageing without consulting a qualified healthcare professional.