Scientists are increasingly interested in metformin, a widely used type 2 diabetes drug, as a potential tool for targeting biological processes associated with aging. A new scientific review suggests the long-established medicine may have effects extending beyond blood sugar control, although whether it can slow aging in healthy people remains uncertain.
Metformin has been prescribed since the 1950s and is included on the World Health Organization’s list of essential medicines. Despite its long clinical history, researchers continue to investigate its effects on cellular pathways, epigenetics and the gut microbiome that could be relevant to longevity and age-related disease.
How metformin acts inside cells
The review, published in Aging, highlights metformin’s effects on cellular pathways associated with aging. One important pathway involves AMP-activated protein kinase, or AMPK, an enzyme involved in regulating cellular energy balance.
AMPK activation can influence mTOR, a protein kinase involved in cell growth and metabolism, as well as processes such as autophagy, in which cells recycle damaged or unnecessary components. Metformin has also been linked to changes in oxidative stress and insulin sensitivity.
Animal experiments provide some of the evidence connecting these pathways with longevity. Increasing AMPK activity can extend lifespan in organisms such as worms, while disruption of AMPK signaling in mice has been associated with shorter lifespan. However, these findings do not establish that metformin will produce comparable longevity effects in humans.
Epigenetics and microbiome effects
Metformin may also influence epigenetic processes, which regulate gene activity without changing the underlying DNA sequence. Researchers have examined its effects on enzymes including TET2, which is involved in DNA methylation regulation.
Through these mechanisms, metformin could potentially influence age-associated epigenetic changes. However, claims that it preserves a “younger” epigenetic state remain under investigation.
A small 2022 study involving 32 people with type 2 diabetes found that metformin users showed epigenetic measures consistent with slower biological aging than non-users. The estimated difference was approximately 2.7 to 3.4 years, but the observational design and small sample mean the finding cannot establish that metformin caused the difference.
Metformin also interacts with the gut microbiome and can alter bacterial communities. Some of these changes have been associated with metabolic and inflammatory processes. Mouse experiments have additionally suggested that microbiome changes associated with metformin may influence tumor growth under certain experimental conditions, including high-fat diets.
Evidence and limits in human studies
Despite promising laboratory and animal findings, evidence that metformin slows human aging remains incomplete. Much of the available clinical and observational research involves people with diabetes or other metabolic conditions rather than healthy adults.
Studies have examined outcomes ranging from mortality and cardiovascular disease to cancer, frailty and biomarkers associated with aging. Because these outcomes differ substantially, it remains difficult to determine whether metformin affects aging itself or primarily improves health through its established metabolic effects.
Observational studies present another challenge because people taking metformin can differ from non-users in their health, medical care and other characteristics.
Randomized clinical trials specifically designed to investigate aging-related outcomes are therefore needed before metformin can be considered a longevity intervention for otherwise healthy people.
Next steps for aging research
One proposed effort is the Targeting Aging with Metformin, or TAME, trial, designed to investigate whether metformin can delay multiple age-related conditions. Plans have called for enrolling approximately 3,000 older adults across several U.S. research centers.
Rather than attempting to prove that metformin directly extends lifespan, TAME is designed around a composite of age-related outcomes, potentially including cardiovascular disease, cancer, cognitive decline and mortality.
If fully funded and conducted as planned, the trial could provide stronger evidence about whether metformin influences multiple age-associated diseases rather than individual conditions alone.
Researchers are also developing biomarkers that could help measure biological aging and responses to interventions. These include epigenetic clocks, molecular signatures in blood and other biological measures that may eventually help determine whether an intervention changes processes associated with aging.
Until stronger clinical evidence becomes available, metformin should not be considered a proven anti-aging treatment for healthy people. It remains a prescription medication with potential adverse effects and established medical indications, particularly in the management of type 2 diabetes.
Nevertheless, evidence involving cellular signaling, epigenetic processes and the microbiome has made metformin an important candidate in geroscience research. Whether these biological effects can translate into longer, healthier lives in people without diabetes remains one of the key questions future clinical studies will need to answer.
