Comparison of metabolic outcomes in patients undergoing laparoscopic roux-en-Y gastric bypass versus sleeve gastrectomy - a systematic review and meta-analysis of randomised controlled trials.

BACKGROUND AND OBJECTIVES: Bariatric surgery is the most effective treatment for morbid obesity and is known to have beneficial effects on glycaemic control in patients with type 2 diabetes mellitus (T2DM) and in diabetes prevention. The preferred type of surgery and mechanism of action is, however, unclear. We performed a systematic review and meta-analysis of randomised controlled trials (RCTs) comparing the effects of laparoscopic roux-en-Y gastric bypass (RYGB) with those of sleeve gastrectomy (SG) on metabolic outcome, with a special focus on glycaemic control.

METHODS: A literature search of the Medline, Pubmed, Cochrane, Embase and SCOPUS databases was performed in November 2014 for RCTs comparing RYGB with SG in overweight and obese patients with or without T2DM. The primary outcome was improvement in postoperative glycaemic control. Secondary outcomes included weight-related and lipid metabolism parameters. Synthesis of these data followed established statistical procedures for meta-analysis.

RESULTS: Sixteen RCTs with a total of 1132 patients with overweight or obesity were included in the analysis. When compared with patients who underwent SG, those who underwent RYGB showed no difference after 12 months in mean fasting blood glucose (mean difference [MD] -6.22 mg/dl, 95% confidence interval [CI] -17.27 to 4.83; p <0.001). However, there was a better outcome with RYGB, with lower mean fasting glucose levels at 24 months (MD -16.92 mg/dl, 95% CI -21.67 to -12.18), 36 months (MD -5.97mg/dl, 95% CI -9.32 to -2.62) and at 52 months (MD -15.20 mg/dl, 95% CI -27.35 to -3.05) mg/dl; p = 0.010) and lower mean glycated haemoglobin (HbA1 at 12 months (MD -0.47%, 95% CI -0.73 to -0.20%; p <0.001) and at 36 months postoperatively compared to SG. Fasting insulin levels and HOMA indices showed no difference at any stage of follow-up. In the subgroup including only diabetic patients HbA1c showed lower levels at 12 months (MD -0.46%, 95% CI-0.73 to -0.20%). No difference was found for the fasting insulin at baseline and after 12 months. Similarly, when compared to SG, patients that underwent RYGB had lower low-density lipoproteins at 12 months. This effect was lost at 36 months. Patients undergoing RYGB also had lower triglycerides at 12 months and at 52 months, lower cholesterol at 60 months and an improvement of BMI at 52 months postoperatively. BMI values at 12 months and low-density lipoprotein levels at 12 and 36 months were lower for diabetic patients only, as in the overall analysis.

CONCLUSION: Based on this meta-analysis, RYGB is more effective than SG in improving weight loss and short- and mid-term glycaemic and lipid metabolism control in patients with and without T2DM. Therefore, unless contraindicated, RYGB should be the first choice to treat patients with obesity and T2DM and/or dyslipidaemia.