FRIDAY, Jan. 6 (HealthDay News) -- Weight loss surgery isn't likely to cure type 2 diabetes, but it can improve blood sugar control, a new study suggests.

Obesity is a major risk factor for diabetes. Some previous research has suggested that gastric bypass surgery can cure diabetes in up to 80 percent of patients. Gastric bypass, which involves stapling the stomach to form a smaller pouch and connecting it to the small intestine, is considered the most effective type of weight loss surgery.

In this study, researchers at Imperial College London in England used new criteria to assess the effects of gastric bypass and two other types of weight loss surgery in 209 patients with type 2 diabetes.

They found that remission occurred in only 41 percent of patients who had gastric bypass surgery, 26 percent who had sleeve gastrectomy (surgical removal of part of the stomach), and 7 percent of those who had gastric banding, in which a band is used to restrict stomach size.

Complete remission is the return to normal measures of glucose metabolism without taking diabetes medications at least one year after weight loss surgery, according to a definition developed by a group of experts recently brought together by the American Diabetes Association.

"Using the new criteria, we don't get such eye-catching figures as some that have been quoted in recent years," study leader Dr. Carel le Roux, of the department of medicine at Imperial College London, said in a college news release. "But it's clear that weight loss surgery, particularly gastric bypass, has a significant beneficial effect on glucose control."

The researcher added that diabetes "is a chronic, multi-system disease. Stomach surgery may not mean that patients can stop taking diabetes medication, but surgery and medication together achieve better results than either treatment on its own."

The study appears in the January issue of the British Journal of Surgery.

More information

The U.S. National Institute of Diabetes and Digestive and Kidney Diseases has more about weight loss surgery.