Exploring Bariatric Surgery’s Potential as a Diabetes Therapeutic

By Thomas Crocker
Sunday, November 1, 2015

Two types of bariatric surgery were markedly more effective than lifestyle interventions alone at producing at least partial remission of Type 2 diabetes, according to a recent study. The findings add to the evidence of weight-loss surgery’s effectiveness as a diabetes treatment for certain individuals.

Anita P. Courcoulas, MD, MPH, FACS, Professor of Surgery and Director of Minimally Invasive Bariatric and General Surgery at the University of Pittsburgh Medical Center, and co-investigators conducted a nearly five-year clinical trial at UPMC. Sixty-one patients with Type 2 diabetes were randomized into either three years of lifestyle interventions — one year of intensive education and behavior modification, followed by two years of lower-level intervention — or one of two types of bariatric surgery, Roux-en-Y gastric bypass or laparoscopic adjustable gastric banding. Following Year 1 of the study, surgical patients also underwent low-level lifestyle interventions. One-year results of the study were published in JAMA Surgery in 2014; three-year findings appeared in the journal in July.

Fifty of the study participants were women, and 43 percent of participants had a body mass index (BMI) of 30 to 34.9, defined as class 1 obesity. Forty-one patients underwent bariatric surgery — 20 had gastric bypass and 21 had gastric banding — and 20 received only lifestyle interventions. During the first year of the study, the nonsurgical cohort attended weekly sessions in which they received nutrition and exercise information for six months, followed by six months of twice-monthly sessions and twice-monthly check-in phone calls. These individuals were asked to follow a diet of 1,200 to 1,800 kilocalories per day and perform up to 60 minutes of moderate-intensity exercise five days per week. During the second and third years of the study, both surgical and nonsurgical patients attended a monthly lifestyle intervention session, received a monthly phone call and attended periodic update classes.

Stark Gap in Outcomes

After three years, 40 percent of gastric bypass patients had experienced partial or complete remission of diabetes, as had 29 percent of gastric banding patients. Sixty-five percent of individuals who had gastric bypass and 33 percent of individuals who had gastric banding were able to discontinue oral medications or insulin. None of the lifestyle intervention-only patients achieved even partial diabetes remission or were able to stop taking medications.

“Surgical treatments were more effective for Type 2 diabetes remission than nonsurgical treatments, but the rate of remission declined in the gastric bypass group from Year 1 to Year 3 and was stable in those who underwent gastric banding over the same period,” Dr. Courcoulas says. “We were surprised that, even at Year 1, after an intensive lifestyle program, no one in the lifestyle intervention-alone group experienced remission. This is different than in the Look AHEAD study [a multisite, randomized clinical trial that examined the effects of weight-loss lifestyle interventions on a variety of conditions, including Type 2 diabetes], where the intensive intervention did lead to some disease remission. We suspect the explanation for this may be that people who are willing to join a trial with a surgical treatment arm may have more severe disease or may respond to lifestyle intervention differently than people who would volunteer for a nonsurgical study.”

The odds are stacked against the effectiveness of lifestyle interventions alone, says Michel Gagner, MD, FRCSC, FACS, FASMBS, Professor of Surgery at the Herbert Wertheim College of Medicine at Florida International University and Senior Consultant at the Hôpital du Sacré-Coeur de Montréal in Canada.

“Lifestyle intervention has a 95 percent chance of failure with our current modern lifestyle because we are competing against genetic profiles that set a certain metabolic rate and body weight,” says Dr. Gagner, who was not involved with the study. “It was different when people were working mostly in rural settings and having a high caloric expenditure. We [would] have to modify our lifestyle to reproduce a 19th century pattern of caloric expenditure, i.e. more than 3,000 kilocalories a day [for lifestyle interventions alone to be successful at remediating diabetes].”

Lifestyle modification remains an important adjunct to any diabetes treatment, Dr. Courcoulas says, but based on the results of her study, it is insufficient on its own to trigger remission.

Clinical Implications

“People with obesity and a BMI between 30 and 40 with Type 2 diabetes should consider a surgical option in discussions with their primary treating physician or endocrinologist and a metabolic/bariatric surgeon,” Dr. Courcoulas says. “Individuals who have failed maximum medical therapy and those with disease that is difficult to control are likely candidates for a surgical approach. This growing body of longer-term evidence should also be considered by payers to now include coverage for metabolic procedures for those people with class 1 obesity and diabetes.”

Dr. Gagner believes bariatric surgery for diabetes should become as commonplace as one of heart surgery’s staple procedures.

“We should be doing bariatric surgery [for diabetes] as frequently as coronary bypass,” he says.