A piece by author David Stipp gives an overview of the past few years of research into the effects of rapamycin: "The first strong evidence that a drug could slow aging in mammals came out in 2009 when scientists reported that chronically feeding doses of rapamycin to mice significantly extended their average and maximum lifespans. Yet rapamycin, a drug used to help prevent rejection of transplanted organs, causes multiple side effects in people, including elevated triglycerides and cholesterol, increasing the risk of heart disease; moderate immune suppression, perhaps increasing infection risks; and low blood platelet levels, which raises the specter of dangerous bleeding. In recent years another especially surprising and troubling side effect has come to the fore: Chronically taking large doses of rapamycin induces 'insulin insensitivity' in both rodents and humans, leading to rising blood sugar and potentially to type 2 diabetes. How do we reconcile such adverse effects with the drug's unprecedented ability to boost healthy aging and longevity, at least in mice? Some telling insights on this burning issue were recently published in two reports on rapamycin's effect on insulin and blood sugar: a mouse study that revealed a probable mechanism behind the effect and a theory paper suggesting that the purported diabetes risk has been overblown."