Scientists published a review in the journal Aging stating that metformin, a drug widely used to treat type 2 diabetes, potentially affects multiple biological aging mechanisms and increases healthy lifespan. ^[1] In male monkeys receiving the drug for 40 months, scientists previously observed signs of reduced tissue biological age, with brain age markers decreasing by nearly six years. ^[2] Metformin activates the AMPK protein, which responds to energy deficiency and triggers cellular restoration and autophagy, the removal of damaged cell components. ^[3] The authors of the review combined results from studies on cells, animals, and humans accumulated over several decades regarding metformin. ^[4] A review by Jarra Manneh and colleagues, published in the journal Aging in 2026, concluded that metformin acts as a geroprotective agent targeting biological root causes of aging and potentially improving health span. ^[5] The Aging review reported that male monkeys treated with metformin for 40 months showed biologically younger tissues, with brain age reversed by nearly 6 years, roughly equivalent to 18 human years. ^[6] The review cited observational human data indicating that people taking metformin had biological ages up to 3.43 years younger, and that people with diabetes taking the drug lived up to 15% longer than peers without diabetes. ^[7] The review noted that evidence for metformin's anti-aging effect is inconsistent, including a widely publicized study linking metformin to a survival advantage in humans that faced criticism after other researchers could not reproduce its results. ^[8]