Is Weight Loss Surgery the Answer for Diabetes?

with Anita P. Courcoulas MD, MPH

Is weight-loss surgery better than focused dietary intervention and a physical activity plan alone for reversing type 2 diabetes? That controversial question has occupied researchers, doctors, insurers and people with diabetes for more than a decade. Now, a small yet well-designed study seems to have the answer: Yes to surgery.

weight loss surgery University of Pittsburgh researchers randomly assigned 61 obese women and men with type 2 diabetes to receive gastric bypass surgery, an adjustable gastric band or an intensive lifestyle change program. Study volunteers were tracked closely for three years, as scientists monitored their weight, fasting blood sugar, hemoglobin A1c levels (a test of long-term blood sugar control) and use of insulin and other diabetes medications.

Results comparing gastric band surgery to standard therapeutic treatment for diabetes and obesity:

More weight (and fat) lost: Gastric bypass recipients lost an average of 25% of their body weight (and nearly 11% of their body fat), gastric band wearers dropped 15% of their weight (and 5.6% of their body fat) and lifestyle group members lost 5.7% of their weight and 3% of their body fat. People in the gastric bypass also saw their waist size shrink the most, an indicator that they’d lost the most visceral fat – the kind that packs around internal organs and contributes to blood sugar processing problems.

Lower blood sugar:  People in the gastric bypass group saw fasting blood sugar drop 66 mg/dL and their A1c levels fall 1.4%. In comparison, gastric band recipients got a 35-point reduction in fasting blood sugar and a 0.8% reduction in A1c levels. For the lifestyle-only group, fasting blood sugar fell an average of about 28 mg/dL but A1c levels rose slightly.

Less diabetes medication: After three years, 65% of the gastric bypass group and 33% of the gastric band group no longer needed blood sugar-lowering drugs, but no one in the lifestyle change group stopped using diabetes medications.

Diabetes remission: Diabetes was in partial or complete remission for 40% of the gastric-bypass group, 29% of the gastric band group and nobody in the lifestyle intervention group. Partial remission was defined as an A1c level below 6.5% and a fasting blood sugar level of 100-125 mg/dL after one year without medication. Complete remission meant an A1c below 5.7% and a fasting blood sugar level of 100 mg/dL or lower after a year without medication.

Better cholesterol and blood pressure levels, too. People in the gastric bypass group also saw their blood pressure fall by 5.7 to 13 mm Hg, their triglycerides (a blood fat) drop 95 mg/dL and levels of “good” HDL cholesterol rise 16 mg/dL. Gastric band recipients got smaller improvements in triglycerides and HDLs, but blood pressure increased very slightly. Lifestyle-change group members got very small improvements in all three.

"Our study shows that gastric band is better than intensive lifestyle treatment alone for diabetes remission and glycemic control, but is not as effective as gastric bypass, at least at three years," notes lead researcher Anita P. Courcoulas MD, MPH, FACS, professor of surgery and director of minimally invasive bariatric & general surgery at the University of Pittsburgh Medical Center.

Of note: People with stage 1 obesity (a body mass index (BMI) between 30 and 35) improved just as much as those with  stages 2 or 3 obesity. While gastric band surgery is FDA-approved for people with stage 1 obesity and related health problems such as diabetes, more invasive weight loss surgeries like gastric bypass and sleeve gastrectomy are not.  So far, the American Diabetes Association and the American Society for Metabolic and Bariatric Surgery’s position is that weight-loss surgery may be an option for people with a BMI over 35 with a health problem like diabetes.  A growing number of research studies are looking at the procedure in people with stage 1 obesity.

Courcoulas says this new study provides information about long-term results that could help lead more insurers to cover weight-loss procedures for people with a BMI of 30-35. “Forty-three percent of our participants had a BMI below 35, the group for whom data is lacking,” she notes. “Our results do show that gastric bypass and gastric banding are superior to intensive lifestyle treatment alone for type 2 diabetes remission for people in this lower BMI group. Our study is small, but rigorous and does add data supporting the utility of bariatric surgery in this lower BMI population. I do believe that the growing body of data [and] evidence, including this current study, may effect change in health care coverage."

Jane Chiang, MD, senior vice president of medical affairs and community information for the American Diabetes Association (ADA), told EndocrineWeb that while the ADA does not think there’s enough evidence to suggest surgery for people with mild obesity, the “ADA’s Professional Practice Committee (who write the ADA Standards of Medical Care) will carefully evaluate this study and will consider its impact on our clinical practice recommendations.

The Pros and Cons of Gastric Bypass Surgery

Gastric bypass surgery (also called Roux-en-Y gastric bypass) involves stomach-stapling that reduces it to a pouch about the size of a small lemon. The stomach is then re-routed to bypass the upper portion of the small intestine. Gastric bypass surgery reduces the amount of food the stomach can handle and calorie absorption.

Adjustable gastric band surgery involves placing a band around the upper portion of the stomach to create a small pouch, restricting food passage. This causes a decrease in food intake. 

After both procedures, people must follow a reduced-calorie meal plan to lose weight. For the study, people in the intensive lifestyle change group followed a low-calorie, high-fiber meal plan and were encouraged to be physically active regularly.

Weight loss surgery may improve blood sugar control by altering levels of gut hormones, as well as by speeding up weight loss. It may also alter the balance of microbes in the digestive system in beneficial ways. Courcoulas says more research into the exact mechanisms is needed. And, she adds, so are longer studies about weight-loss surgery’s effects. She is currently at work on a seven-year study with researchers from the University of Washington in Seattle, the Joslin Diabetes Center in Boston and the Cleveland Clinic.

EndocrineWeb Medical Advisory Board member J. Michael Gonzalez-Campoy, MD, PhD, FACE,  and medical director and CEO of the Minnesota Center for Obesity, Metabolism and Endocrinology agrees that long-term outcomes are necessary to justify the risk of surgery, which include infection, stroke and heart attack. “Obesity and diabetes are chronic diseases.  Surgery may bring about better short term weight loss than lifestyle changes alone. And surgery is expected to bring remission of diabetes in most patients. But all patients need long-term follow-up.”

For now, Courcoulas suggests that people with type 2 diabetes and stage 2 or 3 obesity talk with their doctor about whether surgery is a good option. “I do think it makes sense to consider a surgical option if one’s diabetes is very difficult to control after best attempts at medical and lifestyle management,” she says.




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