Two recent studies have found that weight-loss (bariatric) surgery worked much better than the standard medical treatment of Type 2 diabetes in obese and overweight people whose blood sugar was uncontrolled.

Those who had the surgery, which stapled the stomach and rerouted the small intestine, were much more likely to have a complete remission of diabetes, or need less medicine, than people who were given the typical regimen of diet, exercise and prescription medication. The surgery also helped many to lower their cholesterol and blood pressure to more a more normal range.

The new studies, published in late March by The New England Journal of Medicine, are the first to rigorously compare intensive medical treatment with these particular weight loss operations as ways to control diabetes. Doctors had been noticing incidentally for years that weight-loss operations, also called bariatric surgery, could sometimes get rid of Type 2 diabetes although few randomized controlled studies existed to scrutinize the methods of gaining better blood sugar control with medications versus surgical procedures.

The growing incidence of obesity and type 2 diabetes mellitus is globally recognized as one of the most challenging contemporary threats to public health, and as one editorial in the NEJM put it, “Type 2 diabetes is one of the fastest growing epidemics in human history."

The disease, which causes high blood sugar, is linked to obesity and often becomes very difficult to manage as it progresses. It can bring devastating complications like heart disease, strokes, blindness, kidney failure, poor wound healing, life-threatening infections such as gangrene, and the need for extremity amputation. In the United States, the number of diabetes cases has tripled in the past 30 years to more than 20 million, according to the Centers for Disease Control and Prevention. Most cases of diabetes are Type 2, as Type 1 is far less common, not linked to obesity, and is more genetic in cause, striking people at a younger age.

The question is whether major surgery, with its risks and complications, should be more widely used over more conservative yet less effective pharmaceutical means for blood sugar control. Some surgeons and obesity experts are pushing to establish a role for the surgeries to treat diabetes, not just obesity, while other experts say more research is needed.

Researchers said the operations used in the studies help control diabetes not just because they make people lose weight — a known treatment for the disease — but because the changes in anatomy alter the levels of intestinal hormones that affect the metabolism of sugars and fats.

One of the studies, conducted at the Catholic University in Rome, compared two types of surgery with usual medical treatment. After two years, the surgical groups had complete remission rates of 75 percent and 95 percent; there were no remissions in patients who received medical treatment.

The second study, at the Cleveland Clinic, compared two types of surgery with an intensive medical regimen. The remission rates one year after surgery were lower than in the Italian study — 42 percent and 37 percent — at least in part because the American study used a stricter definition of remission. The intensive medical treatment led to remissions in 12 percent of patients.

Neither study involved the lap band, a popular implanted loop that cinches the stomach into a small pouch and that does not involve cutting or re-routing the stomach or intestines.

The editorial accompanying the studies predicted that the new findings would have a major effect on diabetes treatment and said that the operations “might well be considered earlier in the treatment of obese patients with Type 2 diabetes.”

But the editorial also noted that the studies were relatively small and did not go beyond two years; it was also unclear whether the surgery would help diabetic patients who were not obese, or just not as heavy as those in the studies. The operations in the studies were performed by highly skilled surgeons in well-known obesity treatment centers with rigorous follow-up, and results by others may not be as positive.

According to the American Society for Metabolic and Bariatric Surgery, about 200,000 bariatric operations are performed each year in the United States and range in cost from $11,500 to $26,000, although some insurance plans may cover the procedures. Patients may lose 100 pounds or more after the surgery, which is often kept off with strict maintenance of diet and exercise, with many gaining some weight back and some gaining a lot of the weight back.

Guidelines from the National Institutes of Health say the surgery can be offered to people with a body mass index, or BMI over 40, or over 35 if the person has diabetes or another illness related to obesity. BMI is a calculation that doctors use which correlates the height and weight of an individual according to their gender and age, and places one into a category of normal, overweight, obese, or morbidly obese. The American Diabetes Association also says people with Type 2 and a BMI over 35 should consider the surgery.