Does metformin help you live longer in good health?

Metformin has been a widely used medication for type 2 diabetes for decades, and it has an impressive safety profile. In people with diabetes, it lowers blood sugar, improves insulin sensitivity and protects the blood vessels. This translates into less premature death from cardiovascular disease and lower cancer incidence. In that way, metformin contributes to more healthy years of life -- for this group.

Whether metformin also works as an anti-ageing agent for healthy people without disease is an entirely different question. And honestly, that question has not yet been answered. The large ongoing TAME study was set up specifically to test this, but results are not yet available. Experts disagree on whether metformin produces life-extension in people who do not actually have a medical need for it.

In animal and laboratory research, metformin inhibits several ageing processes simultaneously: it stimulates cellular clean-up, protects DNA and suppresses cells that, as a result of ageing, start secreting harmful substances. In the small roundworm it even extended lifespan, although that turned out to be strongly dependent on gut bacteria and circumstances. What works in a roundworm or cell culture does not necessarily do the same in humans.

Side effects are real. Gastrointestinal complaints are common, and with prolonged use some people develop a deficiency of vitamin B12 or folic acid. That calls for monitoring during long-term use. Use outside a medical indication is not yet supported by clinical evidence in humans.