A systematic review found that, even though Bariatric surgery led to greater weight loss and better glycemic control than nonsurgical treatment among patients with diabetes who were mildly obese, the evidence for long-term efficacy and safety remains limited.

In one of the three randomized studies included in the review, patients who had gastric bypass lost 29.4 kg (64.8 lb) and those who had sleeve gastrectomy lost 25.1 kg (55.3 lbs) over the course of a year, whereas patients on medical therapy lost only 5.4 kg (11.9 lb, P<0.001), according to Melinda Maggard-Gibbons, MD , and colleagues of the University of California, Los Angeles.

Current evidence suggests that, when compared with nonsurgical treatments, bariatric surgical procedures in patients with a body mass index (BMI) of 30 to 35 and diabetes are associated with greater short-term weight loss and better intermediate glucose outcomes. Evidence is insufficient to reach conclusions about the appropriate use of bariatric surgery in this population until more data are available about long-term outcomes and complications of surgery.

Bariatric surgery has demonstrated success for weight loss and comorbidities in morbidly obese patients whose BMI is 35 kg/m2 and higher, but whether individuals with less severe obesity and diabetes could also benefit has been controversial. To examine the evidence for this, and to see if outcomes differed with the various procedures, Maggard-Gibbons and colleagues reviewed the literature and identified more than 50 studies with either direct or indirect comparisons.

In two of the three randomized trials, which altogether totalled 290 participants, patients not within the target population of BMI between 30 and 35 kg/m2 (the mean was 37) were included, but the reviewers considered the data to be "informative" nonetheless.