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Diabetes has historically been considered a disease that is managed medically. A myriad of options exist including diet and lifestyle changes, many different forms of oral hypoglycemics, and insulin therapy. However, adherence to lifestyle changes and daily medications is difficult, and many patients develop uncontrolled diabetes with serious consequences. In the past few decades, bariatric surgery has emerged as a viable treatment option for patients with type 2 diabetes, obesity, and other associated comorbidities. But, how does surgery compare to medical management and can the response be sustained long-term?
To answer these questions, the randomized-controlled STAMPEDE trial compared intensive medical therapy alone to intensive medical therapy plus surgery (Roux-en-Y gastric bypass or sleeve gastrectomy) in 150 patients with type 2 diabetes (glycated hemoglobin >7.0%) and obesity (BMI, 27-43 kg/m2; mean BMI 36; 34% had BMI <35). One- and 3-year outcomes showed that surgical therapy was superior to intensive medical therapy alone in achieving excellent glycemic control (HbA1c <6.0%), improving cardiovascular risk and quality of life, and reducing medication usage.
In this week’s issue of NEJM, the authors report 5-year outcomes from STAMPEDE in the 134 patients who completed the 5-year follow-up (38 patients in the medical-therapy group, 49 in the gastric-bypass group, and 47 in the sleeve-gastrectomy group). The primary outcome was the rate of patients who achieved glycated hemoglobin ≤6.0%, with or without diabetes medications. Additional prespecified secondary outcomes included measures of glycemia, weight loss, blood pressure, lipid levels, renal and ophthalmic outcomes, medication use, adverse events, and quality of life.
After 5 years, when compared to intensive medical therapy alone, the proportion of patients who achieved the primary outcome was greater among patients undergoing gastric bypass surgery (5% vs. 29%; P=0.01, unadjusted; P= 0.03, adjusted; P= 0.08, intent-to-treat) and among patients undergoing sleeve-gastrectomy (5% vs. 23%; P=0.03, unadjusted; P= 0.07, adjusted; P= 0.17, intent-to-treat). Duration of diabetes (<8 years), randomization to gastric bypass, and weight loss at 1 year were associated with achieving a glycated hemoglobin <6.0%.
All changes from baseline in measures of glycemic control were superior in the surgery group compared with the medical-therapy group. Surgical patients also had a significant decrease in the use of cardiovascular and glucose-lowering medicines (including insulin) compared to patients in the medical-therapy group. Within the surgical group, significantly more patients who underwent gastric bypass no longer needed glucose-lowering medications than those who had received sleeve gastrectomy. Additional secondary outcomes that showed an advantage for patients in the surgery group were weight loss (greater for gastric bypass than sleeve gastrectomy), lipid levels, and blood pressure.
Quality-of-life measures (general health and physical functioning, energy-fatigue, bodily pain) among patients in the surgical arm were generally improved compared with no change or worsening among patients in the medical-therapy arm. However, emotional well-being worsened slightly for those who underwent gastric bypass. Some adverse outcomes differed between groups: four patients in the surgical arm required repeat surgical intervention in the first year and the rate of mild anemia was significantly increased in surgical patients compared to medical patients. However, 19% of medical patients experienced excessive weight gain over 5 years compared to none in the surgical arms (a statistically significant difference). No other significant differences in adverse outcomes were reported, although the study was not powered to detect these differences.
This study was the first randomized-controlled trial of bariatric surgery to include patients with mild obesity (BMI, 27-34) and demonstrate a benefit in diabetes control for this population (although this was a secondary outcome). Patients with mild obesity generally are not covered by insurance to undergo bariatric surgery. Therefore, the study results have the potential to influence future insurance coverage and treatment strategies for patients with mild obesity and diabetes.
Overall, surgery was more effective than medical therapy in controlling diabetes in patients with obesity, including mild obesity. The authors comment, “The results of surgery are striking in this population with long-standing, uncontrolled diabetes.” They found that duration of diabetes <8 years was the main predictor of achieving favorable glycated hemoglobin with surgery, and therefore emphasize “the importance of early surgical intervention for maximal glycemic benefit” in this population.
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Andrea Merrill, MD
Andrea was a 2015-2016 NEJM Group Editorial Fellow. She is currently in the middle of her General Surgery residency at Massachusetts General Hospital and is also conducting research focusing on improvements in breast cancer surgery. She plans to pursue a fellowship in Surgical Oncology at the completion of her residency.