A new study published Thursday, March 17, in Diabetologia pitted bariatric surgery against an intensive diet and exercise regimen to see how each would fare in successfully treating type 2 diabetes — and surgery came away the far and clear winner.

The authors recruited 32 patients with mild to moderate obesity and type 2 diabetes, randomly placing them into one of two groups. Fifteen received laparoscopic Roux-en-Y gastric bypass surgery; 17 enrolled in a rigorous lifestyle intervention program. By one year’s time, 60 percent of the bariatric group had achieved complete remission of their condition, compared to 6 percent of the diet and exercise group. The former group also achieved greater average weight loss than the latter, but the researchers believe that alone didn’t explain the overwhelming difference in success rates. Additionally, some of these success stories came from patients with a Body Mass Index (BMI) ranging from 30 to 35, a group typically below the eligibility waterline for surgery.

“These findings call into serious question the longstanding practice of using strict BMI cutoffs as the primary criteria for selection for bariatric surgery among patients with type 2 diabetes,” they wrote.

Hoping to improve on previous randomized trials comparing surgery to lifestyle interventions, which showed similar findings, they designed a particularly dedicated regimen for the intervention group. These patients attended weekly group nutrition sessions and, for the first six months, were asked to visit an exercise facility three times a week for 45-minute sessions while completing another two sessions at home. For the next six months, they were allowed to complete four of five sessions at home.

For the surgery group, patients were given a 10-month behavioural treatment regimen following the procedure and asked to attend several bariatric support group meetings. For a Roux-en-Y gastric bypass, surgeons staple shut the majority of the stomach, leaving behind only a small pouch that they then directly attach to the lower small intestine. This both decreases the amount of food that can be in the stomach at any time and dramatically reduces the digestive system’s ability to absorb calories and other nutrients from the food that is eaten.

Those given diet and exercise did improve in ways the surgery group didn’t. Their cardiovascular fitness increased, and their lean body mass stayed level even as they lost an average of 6 percent of their starting body weight. Bariatric patients had no significant improvements in fitness and, while they did lose an average 25.8 percent of their original weight, they also lost 10 percent of lean body mass.

However, when it came to escaping the need for medication and maintaining long-term normal blood glucose levels, the bariatric group blew past the others. Both groups had the same level of short term glucose control, but those on diet and exercise achieved this largely by relying on medicine. On the other hand, even bariatric patients who didn’t manage to put their disease into complete remission still needed to take fewer drugs than before. These results were even more impressive considering that the bariatric group had been diabetic for nearly twice as long as the intervention group.

The authors believe the trial, which they called “Calorie Reduction Or Surgery: Seeking to Reduce Obesity And Diabetes Study,” or CROSSROADS, is the most rigorous comparison to come along yet.

“Even completion of what we view as the most intensive lifestyle–medical approach that could reasonably be considered in practice cannot improve diabetes and other cardiovascular risk factors as well as Roux-en-Y gastric bypass,” they concluded.

Despite the impressive victory, gastric bypasses are not a treatment option for the meek. Although safer than they were in the past, they still carry potential health risks, such as malnutrition and fractures. They have also been linked to greater mental health problems following surgery, though the research on this is mixed .

For those facing normally difficult-to-treat conditions like diabetes and morbid obesity , though, it may be a risk well worth taking.

Source: Cummings D, Arterburn D, Westbrook E, et al. Gastric bypass surgery vs intensive lifestyle and medical intervention for type 2 diabetes: the CROSSROADS randomised controlled trial. Diabetologia. 2016.