Bypass Surgery for Diabetes With Nonmorbid Obesity? Maybe

Marlene Busko

June 04, 2013

In 2 new reports, mildly to moderately obese patients with uncontrolled diabetes who underwent bariatric surgery had better short-term glucose control and weight loss than their peers who received medications and lifestyle advice. But the surgery had potential complications, and, more important, it is unknown whether the benefits of the surgical procedure extend beyond 1 to 2 years, the researchers caution.

"What these papers show is that a positive effect on glucose control, diabetes control, and remission of diabetes in the short term can definitely be achieved in most of these patients," lead author of an accompanying editorial, Bruce M. Wolfe, MD, from Oregon Health and Science University, Portland, told Medscape Medical News. But the initial cost is high, surgical "complications may occur, and the longer-term outcomes — 5 years or more — remain to be defined," he added.

"The criterion of a [body mass index] BMI of 30 to 40, which both papers address, is [much] lower than the usual BMI in most bariatric-surgery papers, [which is around] 46 or 48," according to Dr. Wolfe. Determining whether patients with a BMI of 30 to 35 would benefit from bariatric surgery is important, since approximately 4% of the US population has diabetes and a BMI in that range, he noted.

The newly published research includes a randomized controlled trial, the Diabetes Surgery Study, by Sayeed Ikramuddin, MD, from the University of Minnesota, Minneapolis, and colleagues and a systematic review by Melinda Maggard-Gibbons, MD, from the University of California, Los Angeles, and colleagues. Both are published together with the editorial in the June 5 issue of the Journal of the American Medical Association.

Rare RCT of Gastric Bypass for Diabetes

Few previous trials have investigated the merits of bariatric surgery in moderately obese patients with diabetes, and those that did had some limitations, Dr. Ikramuddin and colleagues write.

To examine this further, they conducted the Diabetes Surgery Study, a prospective, randomized clinical trial comparing Roux-en-Y gastric bypass with intensive medical management in a cohort of 120 patients with poorly controlled type 2 diabetes and BMIs from 30.0 to 39.9 who were seen at 3 sites in the United States and 1 in Taiwan.

All patients received intensive behavioral intervention to modify their lifestyles and medications, as needed, to treat hyperglycemia, hypertension, and dyslipidemia, based on the Look AHEAD (Action for Health in Diabetes) protocol.

Half of the patients were randomized to also undergo Roux-en-Y gastric-bypass surgery.

The study's primary 1-year outcome was a triple end point based on recommendations from the American Diabetes Association: HbA1c below 7%, LDL cholesterol below 100 mg/dL, and systolic blood pressure below 130 mm Hg. This was reached by 28 patients (49%) in the gastric-bypass group vs 11 patients (19%) in the lifestyle/medical-management group (odds ratio [OR], 4.8; 95% confidence interval [CI], 1.9 – 11.7). Regression analyses indicated that achieving this composite end point was primarily attributable to weight loss.

Patients who underwent surgery also required an average of 3 fewer medications to manage their medical conditions compared with patients in the control group.

There were 22 serious adverse events in the gastric-bypass group vs 15 in the lifestyle/medical-management group; the 2 most serious complications were related to gastrointestinal anastomotic leakage, and 1 patient suffered anoxic brain injury. Patients who underwent surgery were also more likely to have nonserious adverse events such as nutritional deficiencies.

"Bariatric surgery can result in dramatic improvements in weight loss and diabetes control in moderately obese patients with type 2 diabetes who are not successful with lifestyle changes or medical management," Dr. Ikramuddin and colleagues summarize.

However, "the benefits of applying bariatric surgery must be weighed against the risk of serious adverse events," they caution. The trial should be repeated in a larger sample with longer follow-up, although they note that it was difficult enough to recruit sufficient patients for this trial (22 candidates were screened to enroll every 1 patient).

Review Identifies Only 3 RCTs, Draws Same Conclusions

In their review, Dr. Maggard-Gibbons and colleagues explain that performing bariatric surgery to treat diabetes in individuals with a BMI of 30 to 35 is controversial, largely due to a lack of evidence to support this option.

Their search of the literature for studies comparing surgery vs medical management for nonmorbidly obese patients with diabetes uncovered only 3 randomized clinical trials of 290 patients (170 of whom received surgery); the patients included generally had higher BMI ranges (30 to 40) than what they had planned to study (30 to 35).

Compared with patients who were medically managed, those who had surgery had greater weight loss (range, 14.4 – 24 kg) and better glycemic control (range, 0.9- to 1.43-point improvement in HbA1c levels) after 1 to 2 years.

"Overall, the [data] all consistently find that weight loss and short-term glucose control are better in patients treated with bariatric surgery," Dr. Maggard-Gibbons and colleagues report. The improvements were greater in patients treated with gastric bypass than with gastric banding.

However, they add the same caveat as the other researchers: despite the apparent short-term benefits of surgery for patients with a BMI of 30 to 35 who are unable to attain glycemic control, "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," they conclude.

The Diabetes Surgery Study was supported by Covidien. Dr. Ikramuddin serves on advisory boards for Novo Nordisk, USGI, and Medica; consults for Metamodix; and receives grant support from Covidien, EnteroMedics, and ReShape Medical. Dr. Maggard-Gibbons receives grant support from the Agency for Healthcare Research and Quality (AHRQ). The review article was funded by the AHRQ and the US Department of Health and Human Services. The editorialists have reported no relevant financial relationships.

JAMA. 2013;309:2240-2249; 2250-2261; 2274-2275.

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