Background: Roux-en-Y gastric bypass (RYGB) is effective for type 2 diabetes mellitus (T2DM) patients with a body mass index (BMI) >35 kg/m(2). It is unknown whether it benefits those with a BMI ≤ 35 kg/m(2). In the last decade, the effect of bariatric procedures on metabolic outcomes in individuals who underwent surgery outside National Institutes of Health (NIH) guidelines (BMI ≤ 35 kg/m(2)) was both interesting and controversial.
Objective: We performed a systematic analysis evaluating the effect of RYGB for T2DM patients with a BMI ≤ 35 kg/m(2).
Methods: We searched databases (Embase, Ovid, PubMed, China National Knowledge Infrastructure [CNKI], and Cochrane Library) and relevant journals between January 1980 and October 2013. Keywords used in electronic searching included 'diabetes', 'gastric bypass', 'BMI', and 'body mass index'. Inclusion criteria were as follows: (1) patients who underwent RYGB; (2) sample size ≥ 15; (3) patients with a BMI ≤ 35 kg/m(2); and (4) follow-up ≥ 12 months. Exclusion criteria were as follows: (1) data extracted from a database; (2) trials for sleeve gastrectomy; (3) trials for laparoscopic banding; (4) trials for bilio-pancreatic diversion; and (5) trials for duodenojejunal bypass. Participants and intervention type 2 diabetes patients with BMI ≤ 35 kg/m(2) who underwent RYGB. Two investigators reviewed all reported studies independently. Data were extracted according to previously defined endpoints. A meta-analysis was performed for these parameters, with homogeneity among different trials.
Results: Nine articles fulfilled inclusion criteria. After 12 months, patients with T2DM had a significant decrease in their BMI postoperatively (p < 0.00001, weighted mean difference [WMD] -7.42, 95 % confidence interval [CI] -8.87 to -5.97), and remission of diabetes (glucose: p < 0.00001, WMD -59.87, 95 % CI -67.74 to -52.01; hemoglobin A1c p < 0.00001, WMD -2.76, 95 % CI -3.41 to -2.11). There were no deaths in all trials, and the complication rate was between 6.7 and 25.9 %. Mean length of hospital stay was 2.00 to 3.20 days, and mean operative time was from 72.8 to 112.0 min. In terms of study limitations, publication and selection bias were unavoidable. Trials with small sample sizes were excluded, which may lead to a selection bias.
Conclusion: RYGB was effective for T2DM patients with BMI ≤ 35 kg/m(2). Further clinical studies with long-term follow-up data are necessary to clarify this issue.