BackgroundBariatric surgery has been reported to be an effective treatment for obstructive sleep apnea (OSA). However, this evidence was not enough for different populations. Thus, we conducted a follow-up study to evaluate the effect of bariatric surgery on OSA in a Chinese population with obesity and type 2 diabetes mellitus (T2DM).MethodsFrom May 2011 to March 2014, 72 consecutive subjects with obesity and T2DM were recruited for this study. Before and at least 6 months after the laparoscopic Roux-en-Y gastric bypass (LYGB) surgery, all subjects were asked to undergo a polysomnography test. During the sleep center visit, anthropometric characteristic data, blood samples, and sleep questionnaires were collected.ResultsIn total, 44 Chinese participants with OSA were included in the study. Compared with baseline data, the postoperative anthropometric characteristics, blood measurements, and sleep recording data, such as weight, apnea hypopnea index (AHI), and insulin resistance index, differed significantly (p < 0.001). The change in AHI was correlated significantly with preoperative weight (r = 0.298, p < 0.05), preoperative AHI (r = 0.729, p < 0.001), preoperative waist circumference (r = 0.307, p < 0.05), and preoperative insulin resistance (IR) index (r = −0.301, p < 0.05). Postoperative AHI was correlated significantly with age (r = 0.039, p = 0.039) and preoperative AHI (r = 0.445, p = 0.002), and the following prediction model was generated: log10 (postoperative AHI) = 0.626 × log10 (preoperative AHI) +0.010 × age −0.581.ConclusionsOur findings indicate that LYGB could be an effective therapeutic intervention in the management of OSA for patients with both obesity and T2DM, and the preoperative AHI and age might be important factors that influence the effort of LYGB.Electronic supplementary materialThe online version of this article (doi:10.1007/s11695-014-1510-9) contains supplementary material, which is available to authorized users.