Bariatric surgery is safe option for managing type 2 diabetes in overweight or mildly obese patients

The findings were presented here at ObesityWeek 2015, the largest international event focused on the basic science, clinical application and prevention and treatment of obesity. The weeklong conference is hosted by the American Society for Metabolic and Bariatric Surgery (ASMBS) and The Obesity Society (TOS).

Cleveland Clinic researchers say this study is the largest ever-published series of bariatric surgery in patients with type 2 diabetes and body mass index (BMI) of 35 kg/m² or less. They studied 1,003 patients from North America with a BMI of between 25 and 35, with the average BMI being 33.5 kg/m². Forty-six patients had a BMI of 30 or less. All had weight-loss surgery, or what is known as bariatric or metabolic surgery, between 2005 and 2013. Four-in-10 patients were taking insulin injections and 60 percent were on oral medications for their diabetes before surgery. Data was obtained from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database.

"Bariatric surgery is emerging as a safe and effective option for managing type 2 diabetes in patients with mild obesity," said lead study author Ali Aminian, MD, Laparoscopic and Bariatric Surgeon at the Cleveland Clinic Digestive Disease Institute. "We are seeing significant improvement or remission of type 2 diabetes in most lower BMI patients. Current evidence suggests that baseline BMI is unrelated to diabetes remission following bariatric and metabolic surgery. Our data, which is from a large sample size of patients with type 2 diabetes, shows a modest early morbidity (4%) and low mortality (0.2%) following bariatric surgery in non-severely obese patients. These data are important because most patients with diabetes fall into this BMI category."

According to guidelines from the National Institutes of Health (NIH), a person is overweight if their BMI is between 25 and 30, and considered to have obesity, if their BMI is 30 or more. Severe obesity begins at a BMI of 35 kg/m². The NIH guidelines, which have not been updated since 1991, consider surgery an option only for people with a BMI of 35 or more with one or more obesity-related conditions such as diabetes or a BMI of 40.

Dr. Aminian said over the last quarter century, however, the field of bariatric surgery has significantly evolved with introduction of new less invasive surgical approaches (e.g. laparoscopic surgery) and surgical procedures (e.g. sleeve gastrectomy), which have led to improvement in the safety profile of surgery.

The study showed bariatric and metabolic surgery had a high degree of safety in lower BMI patients. The operations included gastric bypass (57%), gastric banding (23%), sleeve gastrectomy (19%) and duodenal switch (1%). The 30-day postoperative mortality rate was 0.2 percent and the cumulative rate of 16 postoperative adverse events was 4 percent. The procedures were generally two hours in length and patients were discharged from the hospital within two days.

"A two-hour operation and a two-day hospital stay has the potential to resolve or improve what is a chronic, progressive and dangerous disease," said John M. Morton, president of the ASMBS and Chief, Bariatric and Minimally Invasive Surgery, Stanford University School of Medicine, who was not involved in the study. "The risk-benefit profile that has emerged for bariatric surgery in people with type 2 diabetes and low BMIs is very favorable and should be considered as a treatment option in carefully selected patients."

Last year, Cleveland Clinic researchers presented a study that found the 30-day complication rate associated with metabolic surgery, specifically gastric bypass in patients with type 2 diabetes and BMIs of 35 or more, was 3.4 percent, about the same rate as laparoscopic cholecystectomy (gallbladder surgery) and hysterectomy. Hospital stays and readmission rates were similar to laparoscopic appendectomy. The month-long mortality rate for metabolic or diabetes surgery was 0.3 percent, about that of total knee replacement, and about one-tenth the risk of death after cardiovascular surgery (Published in the Diabetes, Obesity & Metabolism journal 2015; 17(2):198-201).

Previous studies have shown that metabolic and bariatric surgery improves type 2 diabetes in nearly 90 percent of patients and diabetes goes into remission in up to 50 percent.

In addition to Dr. Aminian, study authors of the abstract entitled, "A Nationwide Safety Analysis of Bariatric Surgery in Nonmorbidly Obese Patients with Type 2 Diabetes," include John Kirwan, PhD; Bartolome Burguera, MD, PhD; Stacy Brethauer, MD; and Philip Schauer, MD, all from Cleveland Clinic.