Impact of gastrointestinal bypass on nonmorbidly obese type 2 diabetes mellitus patients after gastrectomy

Background Our objective was to investigate the predictive preoperative factors and surgical components for type 2 diabetes mellitus (T2D) improvement in patients with body mass index (BMI)<35 kg/m². Methods All patients undergoing curative surgical resection for gastric cancer involving Billroth I gastroduodenal anastomosis, Billroth II gastrojejunal anastomosis (B-I, B-II), or Roux-en-Y total gastrectomy (RYTG), from 2008-2011, were retrospectively reviewed. Of these, 90 patients with T2D were analyzed. The study population was divided into the "improved" and "not improved" groups. The preoperative and postoperative data were assessed using multiple logistic regression analysis. To assess the necessary surgical elements, the gastrointestinal reconstruction methods were categorized according to the presence of the fundus and gastrointestinal bypass. Results Fifty-four patients (60%) experienced improvements in their T2D 2 years after surgery. Lower preoperative glycated hemoglobin (A1C) (odds ratio [OR]:.502; 95% confidence interval [CI]:.313-.804; P =.004), not using multiple oral antidiabetic medications (OR:.341; 95% CI:.120-.969; P =.043), and high BMI before surgery (OR: 1.294; 95% CI: 1.074-1.559; P =.007) were identified as independent predictors of T2D improvements. RYTG was more effective at improving T2D than B-I (OR:.160; 95% CI:.032-.794; P =.025). Statistical analysis according to the surgical elements showed that the bypass procedure was associated with T2D improvements (OR: 3.023; 95% CI:.989-9·240; P =.052). Conclusion Gastrointestinal bypass significantly contributes to T2D improvements in patients with BMI<35 kg/m². Low A1C, high BMI, and not using multiple antidiabetic medications were important predictors of T2D improvement.