Bariatric surgery—either gastric bypass or sleeve gastrectomy—is recommended for people with type 2 diabetes and a body mass index of 40 or above. But the optimal treatment remains unclear and may depend on the severity of the patient’s diabetes.

Using data from previous studies and databases, researchers at Columbia University’s Vagelos College of Physicians and Surgeons, led by Chin Hur, MD, MPH, created a model to investigate the effectiveness, quality of life gains, costs, and complications of gastric bypass, sleeve gastrectomy, and medical therapy among patients over a five-year period.

The study is the first to consider diabetes severity in a comparison of gastric bypass and sleeve gastrectomy, which are the two most popular forms of bariatric surgery in the United States.

Gastric bypass is a more complex procedure than sleeve gastrectomy, and previous studies show it is associated with more complications. Gastric bypass creates a small pouch in the stomach that is attached to the small intestine, so that food bypasses much of the stomach and some of the small intestine. After the surgery, less food can be ingested and absorbed. In sleeve gastrectomy, the stomach is permanently reduced to about one quarter of its original size, but no bypass is created.

The new analysis projected that gastric bypass leads to greater weight loss and a greater rate of remission of diabetes than sleeve gastrectomy or medical therapy, which involves lifestyle counseling and medication.

Gastric bypass surgery also was projected to produce the best results regardless of diabetes severity.

“Determining which groups may benefit from a specific strategy is an important step toward personalized medicine,” says Hur.

“Our study suggests that in most cases, gastric bypass is the preferred strategy when looking at a five-year time frame, despite higher upfront surgical costs and complicati