Bariatric surgery outperforms standard treatment for Type 2 diabetes

Two separate articles published in the March 2012 issue of the New England Journal of Medicine present research showing that weight loss operations (bariatric surgery) worked better than the standard approaches to treating type 2 diabetes in obese and overweight people. In one of the studies, the authors report that most bariatric surgery patients were able to discontinue all diabetes medications and maintain disease remission for the two-year study period, while none of those randomly assigned to receive standard medical treatment did.

“Although bariatric surgery was initially conceived as a treatment for weight loss, it is now clear that surgery is an excellent approach for the treatment of diabetes and metabolic disease,” says senior author Dr. Francesco Rubino, chief of Gastrointestinal Metabolic Surgery and director of the Metabolic and Diabetes Surgery Center at New York–Presbyterian/Weill Cornell and associate professor of surgery at Weill Cornell Medical College.

Type 2 diabetes causes high blood sugar, is linked to obesity and often becomes harder to manage as it progresses—partly because insulin therapy and other hypoglycemic medications often cause additional weight gain. Diabetes can lead to life-threatening complications such as heart disease, stroke, blindness, amputations and liver failure.

In these studies, most surgery patients experienced improvements in blood sugar levels, decreased total cholesterol and triglycerides, and improved HDL-cholesterol concentrations. This suggests that bariatric surgery for the treatment of diabetes may reduce a patient’s cardiovascular risk.

Researchers indicate that the operations used in the studies help control diabetes not just because they help people lose weight, but because the changes in anatomy alter the levels of gut hormones that affect the metabolism of sugars and fats. In fact, diabetes went into remission or was improved immediately after surgery, before patients had experienced any significant weight loss.

One of the studies was conducted at the Catholic University in Rome and evaluated remission of diabetes in 60 severely obese patients (those with a body mass index [BMI] greater than 35) with advanced diabetes. Patients were randomly assigned to three groups: one group underwent Roux-en-Y gastric bypass (RYGB), a second group had biliopancreatic diversion (BPD), and the third group received conventional individualized medication and rigorously monitored dietary and lifestyle modification.

None of the patients in the medical-therapy group has gone into remission since the start of the trial. By contrast, diabetes remission occurred and has been maintained in 95 percent of those who underwent BPD and 75 percent of those receiving RYGB. Remission was defined as fasting glucose of less than 100 mg and hemoglobin A1c (HbA1c) of less than 6.5 percent for at least one year. The authors found that age, gender, preoperative BMI, duration of diabetes and weight loss after surgery were not predictors of diabetes remission.

The second study, performed at the Cleveland Clinic, also compared two operations with an intensive medical regimen. The remission rates at one year after surgery were lower than in the Italian study, but this difference may have been the result of a stricter definition of remission.

“These findings confirm that the effects of bariatric surgery on type 2 diabetes may be attributed to the mechanisms of surgery rather than the consequences of weight loss,” says Dr. Geltrude Mingrone, Department of Medicine, Universita Cattolica S. Cuore, Rome, Italy. “Studying the actual mechanisms by which surgery improves diabetes may help understand the disease better,” she adds.

In spite of the potential gains, however, access to surgery for those eligible is very limited, and barriers are substantial. Less than 2 percent of eligible patients have access to bariatric/metabolic surgery in the United States, and the figure is even lower in the rest of the world. The authors hope their study will help change the way bariatric surgery is perceived and that based on these findings, physicians will consider surgery in the treatment of diabetes.