A review of more than 50 studies found limited evidence supporting the use of bariatric surgical procedures for non-morbidly obese adults (body mass index [BMI] 30-35) with diabetes or impaired glucose intolerance, according to a study in the June 5 issue of JAMA. For the limited data that was available for this patient group, bariatric surgery was associated with greater improvements in short-term weight loss, intermediate blood glucose levels, blood pressure, and high cholesterol than nonsurgical interventions such as medications, diet, and behavioral changes.
"Bariatric surgery is often used to promote weight loss and manage obesity-related comorbidities [co-existing illnesses] in morbidly obese patients (body mass index [BMI; 35 or greater]). In this population, procedures such as laparoscopic adjustable gastric banding and Roux-en-Y gastric bypass have resulted in better glucose control and more weight loss at 1 or 2 years than nonsurgical therapy," according to background information in the article. "Bariatric surgical procedures are being advocated as a treatment for diabetes in less-obese individuals (BMI, 30-35). 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 U.S. Food and Drug Administration has approved gastric banding for individuals with a BMI of 30 to 35 who have an obesity-related comorbidity."
Melinda Maggard-Gibbons, M.D., M.S.H.S., of Rand Health, Santa Monica, Calif., and colleagues conducted a systematic review of the relative benefits and risks associated with surgical and nonsurgical therapies for treating diabetes or impaired glucose tolerance in patients with a BMI of 30 to 35. The authors conducted a search of the medical literature and identified 32 surgical studies, 11 systematic reviews on nonsurgical treatments, and 11 large non-surgical studies published after those reviews that met criteria for the analysis.
The researchers found that bariatric surgery was associated with greater weight loss (range, 32-53 lbs.) and glycemic control during 1 to 2 years of follow-up than nonsurgical treatment in only three randomized clinical trials (RCTs; n=290). None of these trials had substantial numbers of patients meeting the study criteria: 1 trial of 150 patients with type 2 diabetes and an average BMI of 37; 1 trial of 80 patients without diabetes and BMI of 30 to 35; and 1 trial of 60 patients with diabetes and BMI of 30 to 40 [13 patients with BMI <35]).
Bariatric surgery seemed to be associated with weight loss and diabetes control in observational studies having 1 or 2 years of follow-up with indirect comparisons of evidence (approximately 600 patients) and meta-analyses of nonsurgical therapies (containing more than 300 RCTs).
Surgeon-reported adverse events were low (e.g., hospital deaths of 0.3 percent-1.0 percent), but data were from select centers and surgeons. Long-term adverse events are unknown.
"… 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. Until such data are available, the evidence is insufficient to reach conclusions about the appropriate use of bariatric surgery in this patient population, performance of these procedures in this target population should be under close scientific scrutiny, and additional studies comparing procedures are warranted," the authors conclude.
(JAMA. 2013;309(21):2250-2261; Available pre-embargo to the media at http://media.jamanetwork.com)
Editor's Note: This project was funded under a contract from the AHRQ and U.S. Department of Health and Human Services. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, etc.
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