Metformin works by activating AMPK which is an enzyme found within our cells. Some supplements such as Berberine also activate AMPK but have some negative side effects and unknown risks. Metformin has a long history as a drug and seems to be safe with known risks. Metformin works by a similar mechanism as calorie restriction by activating AMPK to at least hypothetically extend life. It does help with insulin resistance by boosting insulin sensitivity which has a whole range of positive benefits.
Should Metformin be sold over the counter? Is it worth it for young people to take it? TAME (Targeting Aging with Metformin) trial is the initial step for determining the effectiveness of Metformin as an anti aging drug.