Bariatric Surgery in Patients with Type 2 Diabetes and Nonmorbid Obesity
EBM Focus - Volume 10, Issue 43
- In patients with type 2 diabetes and obesity, bariatric surgery has been associated with short-term improvements in weight and glycemic control.
- After 3 years of follow-up, bariatric surgery significantly increased the rates of diabetes remission and reduced the need for diabetes medication compared to the intensive lifestyle weight loss intervention in patients with nonmorbid obesity.
The American Diabetes Association recommends considering bariatric surgery in adults with type 2 diabetes and a body mass index (BMI) > 35 kg/m2, especially in patients with difficult to control diabetes or comorbidities (Diabetes Care 2015 Jan;38 Suppl 1:S1). There is insufficient evidence, however, to make generalized recommendations for patients with a BMI < 35 kg/m2. While a few trials have found bariatric surgery improves weight and glycemic control in patients with a BMI between 30 and 40 kg/m2, these trials have been limited by small trial size and follow-up durations of only 1-2 years (JAMA 2013 Jun 5;309(21):2250). One such trial randomized 69 patients with type 2 diabetes and a BMI of 30-40 kg/m2 to 1 of 2 bariatric surgeries (Roux-en-Y gastric bypass vs. laparoscopic adjustable gastric banding) or an intensive lifestyle weight loss intervention (JAMA Surg 2014 Jul;149(7):707). At 1-year follow-up, patients receiving Roux-en-Y gastric bypass had significantly greater weight loss compared to laparoscopic adjustable gastric banding or the intensive weight loss intervention. Both bariatric surgeries were also associated with a significantly greater number of patients achieving partial remission of their type 2 diabetes compared to the intensive weight loss intervention. To determine if bariatric surgery would produce long term diabetes control, 61 patients from this randomized trial who received their randomized treatment were followed for an additional 2 years.
After the initial 1-year follow-up, all patients received a low intensity lifestyle intervention focusing on specific weight loss-related behavioral topics. The 3-year follow-up analyses included 90% of patients receiving Roux-en-Y gastric bypass vs. 95% of patients receiving laparoscopic adjustable gastric banding vs. 70% of patients receiving the intensive weight loss intervention (results reported below). Partial diabetes remission was defined as no use of medication for diabetes mellitus, HbA1c < 6.5%, and fasting plasma glucose ≤ 125 mg/dL (6.9 mmol/L); complete remission was defined as no use of medication for diabetes mellitus, HbA1c < 5.7%, and fasting plasma glucose ≤ 100 mg/dL (5.6 mmol/L).
While this trial was adequately powered to detect differences among groups in diabetes control and weight loss in patients with type 2 diabetes and a BMI of 30-40 kg/m2, the analyses were still limited by the small number of included patients. The trial did not report separate outcomes for patients with class I (BMI 30-34.9 kg/m2) and class II (BMI 35-39.9 kg/m2) obesity, precluding a determination of whether bariatric surgery specifically benefits patients with class I obesity. Also, the results of this trial suggest that Roux-en-Y gastric bypass is associated with superior diabetes control compared to both laparoscopic adjustable gastric banding and the intensive weight loss intervention, but statistics for pairwise comparisons are not reported for these outcomes. Overall, the results of this trial suggest that bariatric surgery may result in persistent diabetes remission for a significant number of patients with type 2 diabetes and nonmorbid obesity.