Gastric Bypass Better Than Intensive Lifestyle Intervention at Controlling Type 2 Diabetes

Commentary by J. Michael Gonzalez-Campoy, MD, PhD, FACE

Overweight and obesity affect two-thirds of Americans. Independent of body mass, adipose tissue disease may develop, also known as adiposopathy. The current approach to overweight, obesity and adiposopathy has shifted from achieving pounds of fat mass loss to returning adipose tissue function toward normal, and rectifying any accompanying metabolic disorders. Since fat mass-related disorders may occur at lower body mass index ranges, the focus of practice is to stratify risk and offer more aggressive approaches to individuals with a higher burden of disease.

In this light, the concept of offering bariatric surgery at a BMI lower than 35 has emerged as a viable option for individuals at high risk. As emerging data on safety and long-term efficacy emerges for bariatric surgery in this patient population, it becomes increasingly important to have appropriate patient selection. Whether a decision is made to refer for surgery or not, all patients must clearly understand that overweight, obesity and adiposopathy are life-long diseases, and life-long regular medical care is necessary. — J. Michael Gonzalez-Campoy, MD, PhD

Obese patients with type 2 diabetes showed greater weight loss and a greater likelihood of partial or complete remission of diabetes at 1 year following gastric bypass surgery compared with gastric banding or lifestyle intervention in a randomized clinical trial reported in the June 4 JAMA Surgery.
Gastric Bypass for Weight Loss - You Are Actually Re-routing Your Stomach in Order to Feel Full and Eat Less“Bariatric surgical procedure options should be considered for those with type 2 diabetes and obesity (BMI 30-40 kg/m2) as they result in better glycemic control and remission of disease than intensive lifestyle treatment alone, in the short term,” said lead author Anita P. Courcoulas, MD, MPH, Professor of Surgery and Director of Minimally Invasive Bariatric and General Surgery at the University of Pittsburgh Medical Center.

“This study is in line with several other studies that show relatively high rates of remission at 12 months with surgery versus conventional medical treatment for type 2 diabetes,” commented Arya Sharma, MD, PhD, Professor of Medicine and Chair in Obesity Research and Management at the University of Alberta, Edmonton, Canada.

In addition, he noted the importance of other two other recently published studies:  1) the 3-year randomized study by Schauer et al showing greater efficacy of gastric bypass and sleeve gastrectomy at achieving hemoglobin levels ≤6% compared with lifestyle intervention (38%, 24%, and 5%, respectively); and 2) long-term prospective data published by Sjöström et al showing diabetes remission rates of 72.3% at 2-years and 30.4% at 15 years following bariatric surgery (gastric bypass or vertical banded gastroplasty) compared with 16.4% and 6.5%, respectively, with non-surgical treatment.

Study Design
In the study by Dr. Courcoulas and colleagues, of 667 adults with type 2 diabetes (BMI 30-40 kg/m2; age 25 to 55 years) who were assessed for eligibility, 69 met inclusion criteria. Of the 69 participants who were randomized, 7 refused the allocated treatment, 1 was excluded for smoking, and  61 underwent one of 3 treatments: Roux-en-Y gastric bypass surgery (RYGB; n=20), laparoscopic adjustable gastric banding (LAGB; n=21), or lifestyle intervention (n= 20) involving an energy-restricted diet, moderate exercise 5 days/week, and behavioral intervention sessions.

Mean weight loss was significantly greater in the RYGB group (-27%) compared with LAGB and the lifestyle intervention groups (-17.3% and -10.2%, respectively; P<0.001). In addition, the rates of partial and complete remission of diabetes were 50% and 17% in the RYGB group and 27% and 23% in the LAGB group (P<0.001 and P=0.047 between groups for partial and complete remission). Both surgery groups also showed significant reductions in the use of antidiabetic medications. In contrast, none of the patients in the lifestyle intervention group experienced partial or complete remission or change in use of antidiabetics.

Three serious adverse events were reported: 1 ulcer in the RYGB group and 2 rehospitalizations for dehydration in the LAGB group. No deaths were reported.

 “In addition, 43% of the subjects in this study had lower BMIs (30-35 kg/m2) where evidence for short-term safety and efficacy of surgical procedures is lacking,” Dr. Courcoulas said. “Important information will come from the longer-term  follow-up of this and other randomized cohorts of people, including those with lower BMIs (30-35 kg/m2) to determine the best treatment for type 2 diabetes in this clinical situation. Dr. Courcoulas said.  

Clinical Implications
“The recent RCT by Courcoulas is another important study in the ongoing debate comparing surgical versus non-surgical treatment of type 2 diabetes in the lower weight spectrum of obesity (BMI 30-40 kg/m2),” commented Melinda Maggard-Gibbons, MD, a surgeon at the David Geffen School of Medicine at the University of California, Los Angeles. “While attempting to rigorously compare outcomes across two procedures versus medical management, it shares characteristics of similar RCTs that limit generalizability—single institution, one surgeon, academic practice, and low enrollment rate (10% of those screened). Enrolled patients may be different in terms of unmeasured factors such as compliance. The study is one of efficacy, not effectiveness across the general bariatric surgery community.

“The study reports improvement of glucose control in the surgical arms. However, baseline levels related to this primary outcome varied. RYGB patients appeared to enter the study with higher A1C and fasting glucose, longer duration of diabetes, and greater percent on insulin (statistical comparisons not reported), thus limiting strong conclusions comparing between procedures or to the control group,” Dr. Maggard-Gibbons said.

“While the modest sample size may not be problematic per se, it impacts extrapolating results to patients with BMI 30-35 kg/m2, as only 40% were in this weight range,” Dr. Maggard-Gibbons said. “Subgroup analyses, and combining patient level data with other RCTs, as appropriate, may prove informative,” she added. Whether or not glucose control is maintained long-term in this weight range is still unknown.  As the authors point out, collaborative multi-site studies with case controlled design and adequate funding to optimize retention may help answer these questions.

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