Bariatric Surgery Not a Cure for Diabetes

Using the recently updated American Diabetes Association (ADA) standard, which defined diabetes remission as hemoglobin (Hb) A1c levels below 6% and fasting glucose levels less than 100mg/dL.(5.6 mmol/L ) at least 1 year after bariatric surgery without hypoglycemic medication, the researchers found remission to be substantially lower than had been reported with earlier criteria.

Using data from 1006 patients, 209 of whom had type 2 diabetes at the time of gastric surgery, and a median follow-up of 23 months postsurgery, complete remission rates, using the new ADA standard, were 40.6% after gastric bypass (65/160 patients), 26% after sleeve gastrectomy (5/19 patients), and 7% after gastric banding (2/30 patients). However, the authors explain, "The remission rate for gastric bypass was significantly lower with the new definition than with the previously used definition (40.6 versus 57.5 per cent; P = 0.003)."  Remission rates for the other 2 procedures were not significantly different according to the new vs the old criteria.

The data, which were collected prospectively in 2 bariatric surgery centers in the United Kingdom and 1 center in Norway, also showed that on average, patients remained obese after surgery (preoperative body mass index [BMI], 48 kg/m² vs postoperative BMI, 35 kg/m²). After surgery, oral hypoglycemic medications were still used by 29.4% of gastric bypass patients, 63% of sleeve gastrectomy patients, and 83% of gastric banding patients.

HbA1c levels were significantly lower after surgery in all 3 surgical groups, with mean levels of 6.2% (compared with 8.1% before gastric bypass), 6.8% (compared with 7.5% before sleeve gastrectomy), and 6.3% (compared with 7.7% before gastric banding; P < .001 for each comparison).

The authors note that these findings are important for "establishing realistic expectations among patients, clinicians, and policy-makers" regarding bariatric surgery in the management of type 2 diabetes. They suggest that emphasis should shift to bariatric surgery as an aid in achieving glycemic control, rather than as a tool for achieving remission.

The authors conclude, "The principal benefit of surgery, however, would not be to improve glycemic control per se but rather to reduce microvascular and macrovascular complications associated with diabetes. The findings of this study emphasize the need for intensive follow-up of patients with type II diabetes following bariatric surgery, in order to review pharmacological treatment, monitor for complications of diabetes, and ensure that adequate glycemic control is achieved."

Br J Surg. 2012:88:100-103.