TAME: The Aging Trial with Metformin That Never Enrolled a Patient

By Alius Noreika

Key takeaways

• TAME, the Targeting Aging with Metformin trial, was designed more than a decade ago and has still not enrolled a single participant.
• It secured FDA agreement on its trial design in 2015, which was the hard regulatory step.
• The obstacle is money. Metformin is off-patent and costs pennies per dose, so no company profits from proving it works.
• Cost estimates for the trial range from roughly $45 million to $75 million across reporting.
• No efficacy results exist. Any claim that TAME has shown metformin slows aging is false.

A trial that exists only on paper

The Targeting Aging with Metformin trial was designed by Nir Barzilai and colleagues at the Albert Einstein College of Medicine, coordinated through Wake Forest University School of Medicine and championed by the American Federation for Aging Research.

The design is a randomised, double-blind, placebo-controlled study of more than 3,000 adults aged 65 to 79 without type 2 diabetes, running six years across 14 US research institutions. Its primary endpoint is a composite: time to first occurrence of cardiovascular disease, cancer, dementia or death.

That composite endpoint is the reason the trial matters beyond metformin. Conventional trials test one drug against one disease. TAME was structured to test whether a single intervention could delay the onset of several age-related diseases at once – treating aging itself as the target rather than its individual consequences.

The trial is designed and regulatory-ready. As of mid-2026 it is awaiting funding, and no participants have been enrolled.

The regulatory step was the easy part

The conventional assumption is that regulators are the barrier to unconventional research. TAME inverts it.

In 2015 the FDA agreed to the trial's design, including its composite endpoint. That was a significant concession, because the agency does not formally recognise aging as a disease that can be treated. Accepting a trial structured around delaying a cluster of age-related conditions established a template that did not previously exist.

Barzilai has described the purpose in those terms: the trial exists less to satisfy curiosity about metformin than to obtain regulatory acceptance for the concept that a drug can delay a cluster of diseases together.

Having cleared that, the trial then spent years in financial limbo. Barzilai has said the team wasted valuable time in funding negotiations with the National Institutes of Health, which was reluctant to sponsor a study in such an unconventional format.

Funding has come close more than once. At one point a private donation appeared to complete the budget and a start date was announced. The trial did not start. In an account of the funding difficulties, Barzilai said a billionaire was initially set to fund the research but subsequently lost his money. The National Institute on Aging set aside roughly $5 million, far short of what the study requires.

The off-patent problem

The reason TAME cannot raise money is straightforward, and it is not about the science.

Metformin has been FDA-approved since 1994, is the first-line treatment for type 2 diabetes in most health systems, sits on the WHO Model List of Essential Medicines, and is taken by hundreds of millions of people. It is generic and costs very little per dose.

That combination makes it an attractive candidate for a population-scale intervention and a commercially worthless one to test. As Barzilai has put it, no pharmaceutical company stands to make money from the result, so none is interested in helping fund it.

The sum involved is not large by clinical trial standards. Reported estimates range from about $45 million to $75 million depending on the source and the year. For a phase 3 trial of over 3,000 participants running six years, that is modest. For a drug nobody owns, it is unreachable.

The frustration Barzilai has voiced is that the commercial weakness and the public value point in the same direction: if the trial found protective effects, the intervention would be one almost anyone could afford.

This is a general problem rather than a quirk of one study. Repurposing cheap existing drugs is among the most promising routes in medicine and among the worst funded, because the financing system that pays for clinical trials is built to reward patent-protected products. Researchers in the field have argued that a public funder – the NIH or the EU – is the only realistic source for this class of study, and that the sums required are small relative to those budgets.

The field moved on

While TAME waited, geroscience did not.

The VITAL-H trial, led by UT Health San Antonio's Barshop Institute, will enrol 726 adults in their 60s and test three FDA-approved medicines – rapamycin, dapagliflozin and semaglutide – against placebo across four arms, with a $38 million budget.

The comparison is instructive.

VITAL-H is smaller and shorter, which makes it cheaper and more fundable. It also tests drugs with commercial futures. Semaglutide in particular sits inside a medicine class generating enormous revenue, which changes the calculus for everyone involved.

Whether the field bypassing TAME is a loss depends on a question the trial was meant to answer. The evidence for metformin's protective effects comes largely from observational studies in people taking it for diabetes, which is a weaker basis than a randomised trial – exactly why the trial was proposed.

A gap bigger than one trial

TAME is the best-known example of a structural problem rather than an exception to one.

Drug repurposing – testing existing, approved medicines for new uses – is attractive for obvious reasons. Safety profiles are already established from years of use in large populations, manufacturing exists, and regulatory pathways are shorter. The cost of establishing a new use is a fraction of developing a compound from scratch.

It is also chronically underfunded, for the same reason TAME is. The clinical trial system is financed largely by companies that expect to recover costs through exclusive sales. Where no exclusivity exists, the incentive disappears regardless of how valuable the answer would be to health systems or patients.

Barzilai has listed a number of other candidate compounds that would benefit from trials of the kind he proposed for metformin. Researchers advocating for this class of work have argued that the sums involved – on the order of $70 million to $100 million to establish reliable aging biomarkers that would make future trials faster and cheaper – are small against the budgets of the NIH or the EU, and that public funders are the only plausible source.

Reliable biomarkers are the practical unlock. If a trial could measure whether an intervention slows aging over two or three years, rather than waiting for disease outcomes over six, the cost of every subsequent study in the field falls sharply. That is a piece of shared research infrastructure, which is precisely the kind of thing markets do not fund and public bodies exist to.

For European readers there is a direct policy question in this. The EU funds collaborative health research at scale through its framework programmes, and the argument that it should back trials of off-patent interventions has been made repeatedly by researchers in the field. Whether it does is a decision about what public research money is for.

What is not established

This is the part that needs stating flatly, because the topic attracts overstatement.

TAME has produced no efficacy results, because it has never run. Any article claiming the trial has shown metformin slows aging is inaccurate. The supporting evidence that motivated it is observational and is not equivalent to proof.

Metformin is also not without complications in this context. Clinical data has indicated that it can blunt some of the cardiovascular adaptations to exercise in older adults – a finding that matters when discussing use by healthy people rather than patients with diabetes, and one reason a randomised trial is needed rather than assumed.

Metformin is a prescription medicine for a specific condition. Nothing here supports taking it to slow aging, and anyone considering it should be having that conversation with a doctor.

The story here is not whether metformin works. It is that a decade after a regulator agreed to the design, the question remains unanswered for want of a sum that would be unremarkable in any commercially sponsored programme. The trial that was meant to establish aging as a treatable target became a demonstration of something else: what medical research does not investigate, and why.

Sources

• Welzo – Metformin and Ageing: The TAME Trial Explained (trial design and status, July 2026): https://welzo.com/blogs/longevity/metformin-longevity
• Science|Business – Anti-ageing therapies: have we got health research funding wrong?: https://sciencebusiness.net/news/drug-development/anti-ageing-therapies-have-we-got-health-research-funding-wrong
• WUFT / NPR – A cheap drug may slow down aging. A study will determine if it works: https://www.wuft.org/2024-04-22/a-cheap-drug-may-slow-down-aging-a-study-will-determine-if-it-works
• MedPath – Metformin's Potential in Slowing Aging to be Examined in TAME Trial: https://trial.medpath.com/news/b4875acf834245dd/a-cheap-drug-may-slow-down-aging-a-study-will-determine-if-it-works-npr
• Longevity.Technology – World's first anti-aging TAME trial gets green-light: https://longevity.technology/news/worlds-first-anti-aging-trial-gets-green-light/
• UT Health San Antonio – UT San Antonio to lead $38 million national trial testing drugs to extend healthspan: https://news.uthscsa.edu/ut-san-antonio-to-lead-38-million-national-trial-testing-drugs-to-extend-healthspan/
• MDLinx – 3 FDA-approved drugs tested in new longevity trial: https://www.mdlinx.com/article/3-fda-approved-drugs-tested-in-new-longevity-trial-inside-the-clinical-debate/6vQTv88VE9h2ReqTkeHV1H
• American Federation for Aging Research – TAME trial: https://www.afar.org/tame-trial