The 4th World Congress on Interventional Therapies for Type 2 Diabetes (WCITD) kicked off on April 8, 2019, in New York City with a welcome address from Francesco Rubino, MD, Congress Director and Chair of Bariatric and Metabolic Surgery at King’s College London. Dr Rubino and other presenters began the 3-day Congress by speaking to attendees from more than 55 countries about the latest data analyzing the effects of bariatric surgery on remission of type 2 diabetes (T2D).1

Ahead of the first Diabetes Surgery Summit held in 2007, only 1 randomized controlled trial (RCT) comparing bariatric surgery and pharmacologic therapy in patients with diabetes was available. Since then, the total has grown to 12 RCTs, 4 of which have been updated since 2016 with longer-term data (3- and 5-year follow-ups).2 These new data indicate significant growth in this area of research and, taken together, support the use of surgical treatment for patients with poorly controlled T2D. In every trial but one, surgery was superior to medical treatment for improving weight loss, hemoglobin A1c levels, T2D remission, and lipid control.2 When comparing results across the spectrum of obesity severity, the trends remained significant in patients with body mass index (BMI) >35 kg/m2 and ≤35 kg/m2.

According to Philip Schauer, MD, Professor of Surgery at the Cleveland Clinic Lerner College of Medicine in Cleveland, Ohio, who presented this update on RCT data, the results across the 12 trials indicate a favorable risk-benefit ratio for metabolic surgery in T2D, with a “reasonable and respectable” complication rate for surgical intervention.2

Indeed, bariatric surgery is well understood to be safe in the short term, with a mortality risk <1% in the 30-day period following surgery.3 Anita P. Courcoulas, MD, MPH, FACS, Chief of the Division of Minimally Invasive Bariatric and General Surgery at the University of Pittsburgh, spoke to the long- and short-term safety of metabolic surgery and indicated that several trials have found no difference in short-term complication rates between patients with class 1 vs class 2 or 3 obesity.3 Dr Courcoulas noted, however, that more comprehensive long-term safety outcome studies are required, as are studies examining nonsurgical safety issues like increased substance abuse and self-harm following gastric bypass surgery.

David Arterburn, MD, MPH, internist and Senior Investigator at the Kaiser Permanente Washington Health Research Institute, also discussed the potential benefits of metabolic surgery on microvascular and macrovascular complications in T2D.4 Randomized trials have not yet shown that intensive lifestyle intervention and pharmacotherapy for diabetes can reduce macrovascular events. To investigate whether metabolic surgery is associated with improvements in long-term risks for macrovascular (eg, coronary artery disease) and microvascular (eg, retinopathy, nephropathy, neuropathy) events in T2D, Dr Arterburn and colleagues performed a retrospective study with a comprehensive control matching process based on age, BMI, and sex, in which they adjusted for dozens of potential confounders.

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After 7 years, people in the nonsurgery control group had a significantly higher rate for microvascular events compared with those who had undergone surgery, with a 60% risk reduction for microvascular disease in the surgical group (hazard ratio, 0.40; 95% CI, 0.30-0.53). The researchers reported a similar trend for macrovascular disease and all-cause mortality; composite index of macrovascular disease was significantly reduced (hazard ratio, 0.58; 95% CI, 0.34-0.99), driven mostly by reduction in coronary artery disease, and there was a nearly 70% reduction in mortality risk.4

Of note, some limitations and precautions regarding interpretation of these data were discussed by an expert panel. William Herman, MD, MPH, Professor of Internal Medicine and Epidemiology at the University of Michigan pointed out that using ‘weight loss’ and ‘medication use’ as outcome measures in studies comparing surgical vs medical therapy in diabetes isn’t appropriate, as these are not specific aims of pharmacologic treatment and will always favor surgical intervention. David Nathan, MD, Director of the Diabetes Center at Massachusetts General Hospital in Boston, Massachusetts, spoke to the need for more compelling evidence before pushing for a major uptake of bariatric surgery in T2D management. With regard to Dr Arterburn’s research, one panelist mentioned “quality of motivation” as a potential unmeasurable confounder in patients who choose to undergo surgery compared with those who choose nonsurgical interventions.

Overall, the first day of WCITD 2019 set the stage for more in-depth discussions on metabolic surgery and T2D among key international stakeholders. “I eagerly look forward to…an exciting event expressly designed to change policies, practices, and the way we think about diabetes and obesity,” stated Dr Rubino.5

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References

1. Rubino F. Introduction of WCITD 2019 from the Congress Director. Oral presentation at: 4th Annual World Congress on Interventional Therapies for Type 2 Diabetes; April 8, 2019; New York, NY.

2. Schauer P. Efficacy of metabolic surgery for T2DM (BMI above and below 35 kg/m2): an update on randomized controlled trials. Oral presentation at: 4th Annual World Congress on Interventional Therapies for Type 2 Diabetes; April 8, 2019; New York, NY.

3. Courcoulas A. Safety of metabolic/bariatric surgery: short- and long-term complications. Oral presentation at: 4th Annual World Congress on Interventional Therapies for Type 2 Diabetes; April 8, 2019; New York, NY.

4. Arterburn D. Effect of metabolic surgery on micro- and macrovascular complications of diabetes and long-term survival. Oral presentation at: 4th Annual World Congress on Interventional Therapies for Type 2 Diabetes; April 8, 2019; New York, NY.

5. Program Book: From Guidelines to Implementation. 4th Annual World Congress on Interventional Therapies for Type 2 Diabetes; April 8, 2019; New York, NY.