Effects of continuous positive airway pressure on glycemic control and insulin resistance in patients with obstructive sleep apnea: a meta-analysis

Previous studies addressing the question of whether continuous positive airway pressure (CPAP) could improve the insulin resistance and glucose control in patients with obstructive sleep apnea (OSA) have led to conflicting results. Therefore, we conducted the meta-analysis to evaluate the effects of CPAP on glycemic control and insulin resistance in OSA patients. We searched PubMed, HighWire Press, Ovid Medline (R), Cochrane library, and EMBASE before December 2011 on original English language studies. The meta-analysis was conducted using Review Manager Version 5. The summary estimate for mean difference of homeostasis model assessment insulin resistance (HOMA) from 12 non-diabetic studies was -0.55 (95 % CI, -0.91 to -0.20; P = 0.002). When compared with fasting blood glucose at baseline, 3 to 24 weeks of CPAP treatment did not improve glycemic control in non-diabetic subjects (-0.12; 95 % CI, -0.3 to 0.06; P = 0.20), as well as in diabetic subjects (-0.71; 95 % CI, -2.24 to 0.83; P = 0.37). There were no intervention-related changes in body mass index. Our analysis showed that CPAP significantly improved insulin resistance in non-diabetic patients with moderate to severe OSA, while no significant change in body mass index was detected. Compared with fasting blood glucose at baseline, there was no change in glycemic control with CPAP. Further large-scale, randomized, and controlled studies are needed to evaluate the longer treatment and its possible effects on weight loss and glycemic homeostasis.