Is Metformin Really a Wonder Drug?

“Is metformin really everything they say it is?” A patient—an intelligent, well-informed woman with children in medicine and an avid reader of article about health—asked me this recently. 
Like her, I often wonder if metformin will catch on as a wonder drug. My patient was likely responding to the increasing amount of research on metformin’s use for conditions other than diabetes and polycystic ovarian syndrome (PCOS) that suggest it might be effective for as many things as a snake oil salesman might imply.

A recent study by Apolzan and colleagues published in Annals of Internal Medicine, "Long-Term Weight Loss With Metformin or Lifestyle Intervention in the Diabetes Prevention Program Outcomes Study" (1), supports some wonder-drug claims. The study showed that metformin helps with weight loss and, most importantly, was associated with sustained weight loss.

Sustained weight loss is the Holy Grail for many patients, and this study showed that “among participants with significant initial weight loss, those who were originally randomly assigned to metformin had greater success in maintaining long-term weight loss (LTWL) than those randomly assigned to lifestyle intervention (ILS) with longer follow-up.”

I do not typically prescribe metformin primarily for weight loss. However, in a patient with prediabetes or PCOS, I have seen people lose weight on metformin. Insulin resistance does something to our bodies, and whether manifested by overt diabetes or not, metformin seems to combat insulin resistance. Apolzan and colleagues’ study gives credence to what clinicians like me see anecdotally.

I’ve written before on this blog how I wish I could prescribe time to patients—time to exercise, time to shop for groceries, time to cook. In our physician toolkit, we have more than medications at our disposal to help patients. However, it is helpful to have clear-cut evidence on a drug that is cheap, is easily accessible, and has a documented association with sustained weight loss.

Even Apolzan and colleagues aren’t ready to claim that metformin is a wonder drug, suggesting that “future investigations should focus on whether metformin could be a useful intervention for LTWL after initial weight loss with lifestyle interventions, antiobesity drugs or devices, or bariatric surgery.”

Reference

1. Apolzan JW, Venditti EM, Edelstein SL, et al. Long-term weight loss with metformin or lifestyle intervention in the Diabetes Prevention Program Outcomes Study. Ann Intern Med. 2019;170:682-90. doi:10.7326/M18-1605