Outcomes of Bariatric Surgery Versus Medical Management for Type 2 Diabetes Mellitus: a Meta-Analysis of Randomized Controlled Trials

Abstract

Introduction: Bariatric surgery improves type 2 diabetes (T2D) in obese patients. The sustainability of these effects and the long-term results have been under question.

Objective: To compare bariatric surgery versus medical management (MM) for T2D based on a meta-analysis of randomized controlled trials (RCTs) with 2 years of follow-up.

Material and methods: Seven RCTs with at least 2-year follow-up were identified. The primary endpoint was remission of T2D (full or partial). Four hundred sixty-three patients with T2D and body mass index > 25 kg/m² were evaluated.

Results: After 2 years, T2D remission was observed in 138 of 263 patients (52.5%) with bariatric surgery compared to seven of 200 patients (3.5%) with MM (risk ratio (RR) = 10, 95% CI 5.5-17.9, p < 0.001). Subgroup analysis of the Roux-en-Y gastric bypass (RYGB) showed a significant effect size at 2 years in favor of RYGB over MM for a higher decrease of HbA1C (0.9 percentage points, 95% CI 0.6-1.1, p < 0.001), decrease of fasting blood glucose (35.3 mg/dl, 95% CI 13.3-57.3, p = 0.002), increase of high-density lipoprotein (HDL) (12.2 mg/dl, 95% CI 7.6-16.8, p < 0.001), and decrease of triglycerides (32.4 mg/dl, 95% CI 4.5-60.3, p = 0.02). Four studies followed patients up to 5 years and showed 62 of 225 patients (27.5%) with remission after surgery, compared to six of 156 patients (3.8%) with MM (RR = 6, 95% CI 2.7-13, p < 0.001).

Conclusion: This meta-analysis shows a superior and persistent effect of bariatric surgery versus MM for inducement of remission of T2D. This benefit of bariatric surgery was significant at 2 years and superior to MM even after 5 years. Compared with MM, patients with RYGB had better glycemic control and improved levels of HDL and triglycerides.

Keywords: Bariatric surgery; Medical management; Obesity; Randomized controlled trial; Treatment outcome; Type 2 diabetes mellitus.