Two-year outcomes from the Diabetes Surgery Study have found that although the addition of gastric bypass to lifestyle and medical management in patients with type 2 diabetes improved diabetes control, adverse events and nutritional deficiencies were more frequent in the surgical group of patients. The paper entitled, ‘Roux-en-Y gastric bypass for diabetes (the Diabetes Surgery Study): 2-year outcomes of a 5-year, randomised, controlled trial, published in The Lancet Diabetes & Endocrinology journal, concluded that “larger and longer studies are needed to investigate whether the benefits and risk of gastric bypass for type 2 diabetes can be balanced.”
The Diabetes Surgery Study is a randomised clinical trial established to determine the relative effectiveness of RYGB combined with intensive medical management (IMM), versus IMM alone, in reducing CVD event rates and mortality in patients with poorly controlled diabetes. IMM will include rigorous lifestyle modification for weight loss and stepped pharmacologic treatment for diabetes and other CVD risk factors. The five-year trial is taking place at four teaching hospitals (three in the USA and one in Taiwan).
The study has recruited 120 patients and with HbA1c of at least 8·0% (64mmol/mol), BMI30-39.9, type 2 diabetes for at least six months and be aged 30–67 years. The patients were randomly assigned to receive either intensive lifestyle and medical management alone (lifestyle and medical management), or lifestyle and medical management plus standard Roux-en-Y gastric bypass surgery (gastric bypass). Drugs for hyperglycaemia, hypertension, and dyslipidaemia were prescribed by protocol.
Sixty patients were assigned to lifestyle and medical management alone and 60 received a gastric bypass. One patient in the lifestyle and medical management group died (from pancreatic cancer), thus 119 were included in the primary analysis. Significantly more participants in the gastric bypass group achieved the composite triple endpoint at 24 months than in the lifestyle and medical management group (26 [43%] vs eight [14%]; odds ratio 5·1 [95% CI 2·0–12·6], p=0·0004), mainly through improved glycaemic control (HbA1c <7·0% [53mmol/mol] in 45 [75%] vs 14 [24%]; treatment difference −1·9% (−2·5 to −1·4); p=0·0001).
There were 46 clinically important adverse events in the gastric bypass group, compared with 25 in the lifestyle and medical management group (mainly infections in both groups [four in the lifestyle and medical management group, eight in the gastric bypass group]). Although the event rate for the gastric bypass group was non-significantly higher than the lifestyle and medical management group (p=0.06).
More fractures were reported in the gastric bypass group (five), compared with one in the lifestyle and medical management group (all the fractures happened in women). In addition, there were many more nutritional deficiencies reported in the gastric bypass group (mainly deficiencies in iron, albumin, calcium, and vitamin D), compared to the lifestyle and medical management group, despite protocol use of nutritional supplements.
Funding for this study was provided by Covidien, National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases Nutrition Obesity Research Centers, and the National Center for Advancing Translational Sciences.