Currently, medical experts do not recommend metformin for healthy individuals for longevity and warn against self-prescribing. Cutler said it is too premature to recommend that everyone use metformin for its purported longevity benefits.
“Metformin has been used for diabetes for almost a hundred years. It is generally safe, well-tolerated, cheap, and effective for treating diabetes and preventing diabetic complications. However, due to its known risks and the unknown benefits in those without diabetes, it is not advisable for healthy people to take metformin for the purpose of improved longevity,” he warned.
“I would not recommend that an otherwise healthy person start metformin solely for longevity outside a clinical trial. That is different from its use for diabetes or for diabetes prevention in selected high-risk people. Someone already taking it for a medical indication should not stop because the longevity question remains unsettled,” Barardo said.
“For healthy people, my main concern is not that metformin is unusually toxic. It is that even a generally safe medicine needs to show enough benefit to justify taking it for years,” he added.
Cutler underscored that, as with all drugs, metformin can also have harmful effects.
“The negative effects include common GI side effects like nausea and diarrhea. Less commonly, but more seriously, is the occurrence of vitamin B12 deficiency caused by metformin. This can lead to anemia, neuropathy and even cognitive decline,” he said.
“Very rarely, a serious condition called lactic acidosis can be caused by metformin,” he continued, adding that people with significant kidney or liver dysfunction are not advised to use metformin.