Evidence is accumulating that bariatric surgery—an extreme measure for the very obese that involves reducing the size of the stomach to promote weight loss—may “cure” diabetes.

I use the word “cure” with caution, because diabetes is complex, and the approach requires more research. But the results are promising enough that a recent International Diabetes Surgery Task Force summit in Italy issued a first-of-its-kind consensus statement pronouncing bariatric surgery to be a “legitimate approach” for diabetes treatment.

“Many patients undergoing surgically induced weight loss appear to have a form of lasting remission of their diabetes,” Dr. Jonathan Purnell, an endocrinologist at Oregon Health & Science University, writes in the Journal of the American Medical Association (JAMA). The change happens quickly. And according to Annals of Surgery, diabetes “typically resolves within days to weeks of surgery—even before patients have lost much weight.”

Doctors are not sure exactly why the surgery works. The task force raised the possibility that the “rearrangement of the anatomy” might have a beneficial effect on certain hormones. Dr. Purnell suggests that excluding certain nutrients from the gut might change how the body reacts to insulin.