The appellation “wonder drug” might even be an understatement, reckons Harvard Health’s Robert Shmerling, MD. But why? Metformin is a first-line treatment for type 2 diabetes; its potential for “possibly even slowing aging and extending life expectancy” is less clear. However, researchers are investigating its apparent ability to lessen cognitive decline, reduce the risk of stroke, treat polycystic ovary syndrome (PCOS), and prevent age-related illness. Move over, artemisinin. And you, amycretin. There’s a new (old) dog in town. A brief history of metforminMetformin’s storied history begins hu…