Gastrointestinal Surgery as a Treatment for Diabetes
Authors: David E. Cummings, David R. Flum
Journal: JAMA (2008)

APPROXIMATELY ONE-THIRD OF ADULTS IN THE UNITED States are obese, and largely because of this, at least as many have diabetes or prediabetes. With these escalating twin epidemics, the health care community has been challenged to develop novel treatment strategies. In this issue of JAMA, Dixon and colleagues report a 2-year study in which patients with recently diagnosed type 2 diabetes and a body mass index (BMI) of 30 to 40 were randomly assigned to receive conventional medical/ behavioral therapy (medical therapy and a focus on weight loss through lifestyle modification) or laparoscopic adjustable gastric banding (LAGB) plus conventional medical/ behavioral therapy. The results were clear and striking. Complete remission of diabetes at 2 years was achieved in 73% of the patients in the LAGB group vs only 13% of those in the medical/behavioral therapy group, and the former experienced larger reductions in blood glucose levels, glycated hemoglobin levels, estimated insulin resistance, use of diabetes medication, and several features of the metabolic syndrome. No serious surgical complications were reported, and minor surgical mishaps seemed no worse than the adverse reactions to diabetes-related pharmacotherapy. As expected, the surgical group lost more weight than the medical/behavioral group (20.7% vs 1.7%), and the amount of weight lost was the dominant predictor of diabetes remission. The percentage weight loss generally required for diabetes resolution was 10%, which was achieved in 86% of surgical patients but in only 1 patient in the medical group. Of the 34 patients who lost less than 10% of body weight, only 4 experienced diabetes remission, and these individuals had particularly mild baseline disease. Conversely, of the 26 patients who lost more than 10% of body weight, diabetes remitted in all but 4. In short, diabetes remission after LAGB appeared attributable to weight loss, with no evidence of additional antidiabetes mechanisms; but by promoting greater weight loss, LAGB was far more effective than medical/behavioral therapy at improving diabetes. For a study in which surgery outperformed nonsurgical interventions, a natural question is whether the medical/ behavioral program was as good as it could be. Pharmacotherapy was determined individually by an experienced diabetologist, using all diabetes medications available at the time. In addition, lifestyle optimization was stressed, including reduced intake of fats, saturated fats, foods with high glycemic index, and overall calories, together with a physical activity program of more than 10 000 steps per day and 200 minutes per week of moderate-intensity exercise. Whether this program constitutes the optimal medical/behavioral intervention can be debated. However, participants visited a physician, nurse, dietician, and/or diabetes educator at least once every 6 weeks for 2 years—an intensity of follow-up unlikely to be exceeded in common practice. Moreover, because both study groups had access to the same nonsurgical interventions, the greater improvement in diabetes following surgery is attributable to the benefits of LAGB in this randomized trial. The general applicability of these findings remains to be determined. The authors’ bariatric surgical team in Melbourne, Australia, is among the most experienced groups in the world using LAGB, and their excellent results may not be readily reproducible elsewhere. Their reported postLAGB weight loss often exceeds that observed by other investigators. The discrepancy likely results from the Melbourne group’s acclaimed long-term, multidisciplinary postLAGB follow-up program. The widespread feasibility and cost of such postoperative coaching are unclear, and results in the community at large are unknown. Moreover, participants in this study had relatively mild diabetes, as characterized by less than 2 years’ duration, no retinopathy or nephropathy, a mean baseline glycated hemoglobin value of 7.7%, and only 1 patient taking insulin. It is unclear whether secondary effects from weight loss alone after LAGB, without apparent direct antidiabetes surgical mechanisms,