Effect of Roux-en-Y gastric bypass on patients with type 2 diabetes mellitus and body mass index of 27.5-35 kg/m2-a single center retrospective cohort study.

Introduction: While Roux-en-Y gastric bypass (RYGB) has been extensively studied in patients with type 2 diabetes mellitus (T2DM) and preserved islet function, the significance of insulin resistance in guiding RYGB treatment remains unclear. This study aimed to evaluate the efficacy of RYGB in T2DM patients with a low body mass index (BMI, 27.5-35 kg/m²), insulin resistance, and impaired β-cell function.

Methods: A retrospective cohort of 34 T2DM patients with low BMI who underwent RYGB at our institution was analyzed. Insulin resistance was assessed using hyperinsulinemic euglycemic clamp. The indicators related to glucose and lipid metabolism were also assessed and collected at baseline and 12 months postoperatively.

Results: Significant reductions in BMI and HbA1c were observed within 12 months post-surgery (P < 0.05). Fasting plasma glucose decreased from 9.40 ± 3.12 mmol/L to 5.87 ± 2.67 mmol/L (P < 0.05). Complete remission rates were 31.25% for T2DM, 100% for hypertriglyceridemia, and 70% for hypertension. Multivariable logistic analysis identified shorter diabetes duration (odds ratio [OR] 0.89, 95% confidence interval [CI] 0.83-0.95, P = 0.025), higher BMI (OR 1.14, 95% CI 1.06-1.34, P = 0.033), and lower peripheral glucose disposal rate (OR 0.95, 95% CI 0.93-0.97, P = 0.043) as independent predictors of diabetes remission.

Conclusions: Patients with T2DM and low BMI who have insulin resistance may still benefit from RYGB, even if they exhibit impaired β cell function. Shorter duration of diabetes, higher BMI and lower peripheral glucose disposal rate were independent predictors of diabetes remission after RYGB.