Weighing in on Weight Surgery

Diabetes patients who are moderately obese may benefit from surgery but more study is needed

(RxWiki News) For obese patients with diabetes, surgery that promotes weight loss may improve blood glucose levels, blood pressure and cholesterol, but the long-term results are debatable.

Surgery that promotes weight loss has been shown to reduce diabetes risk factors among the extremely obese. Some who are moderately obese have also turned to bariatric surgery.

While new research has found that these patients may benefit from these procedures, their effect over time is uncertain and data is limited.

"Ask your doctor about bariatric surgery."

Melinda Maggard-Gibbons, MD, of Rand Health, Santa Monica, California, and colleagues conducted a systematic review of 54 studies related to weight loss and diabetes. They included 32 surgical studies and 22 non-surgical studies.

In their background information, Dr. Maggard-Gibbons and her team stated that the morbidly obese, with a body mass index (BMI) of 35 or greater, had experienced better glucose control and more weight loss at one or two years with surgical procedures than nonsurgical therapy. These procedures include laparoscopic adjustable gastric banding and Roux-en-Y gastric bypass.

The authors added that "...bariatric surgical procedures are being advocated as a treatment for diabetes in less-obese individuals (a BMI of 30 to 35). However, this practice remains controversial. In 2006, the Centers for Medicare & Medicaid Services would not approve coverage for patients with lower BMI and diabetes, whereas the US Food and Drug Administration has approved gastric banding for individuals with a BMI of 30 to 35 who have an obesity-related comorbidity."

The researchers in this study set out to evaluate relative benefits and risks of surgical and nonsurgical therapies for treating diabetes or impaired glucose tolerance among the moderately obese as opposed to the morbidly obese.

From the limited data available on this patient group, bariatric surgery was associated with greater improvements in short-term weight loss, intermediate blood glucose levels, blood pressure and high cholesterol compared to nonsurgical interventions such as medications, diet and behavioral changes.

Only three randomized trials, however, supported these findings, and none of these trials had substantial numbers of patients meeting the study criteria.

In one trial of 150 patients with type 2 diabetes, the average BMI was 37. Another trial evaluated 80 patients without diabetes and with BMIs of 30 to 35. A third study looked at results of 60 patients with diabetes and BMIs of 30 to 40. In that third study, 13 of those patients had BMIs of less than 35. The trials all had one to two years of follow-up with patients.

Surgeon-reported adverse events (such as hospital deaths) were low and long-term adverse events are unknown, according to the authors.

The authors concluded, “...there are limited data from clinical trials in this specific patient population, and it is unknown whether the benefits observed are durable long-term and if these findings might translate into reductions in the microvascular and macrovascular complications of diabetes.”

The scientists recommended additional study to find out about the appropriate use of bariatric surgery in this patient population.

The study was published in the June 5th issue of the Journal of the American Medical Association. This project was funded under a contract from the Agency for Healthcare Research & Quality and the US Department of Health and Human Services.

Review Date: 
June 5, 2013