Effect of Treatment of OSA With CPAP on Glycemic Control in Adults With Type 2 Diabetes: The Diabetes Sleep Treatment Trial (DSTT).

OBJECTIVE: The effect of obstructive sleep apnea (OSA) treatment with continuous positive airway pressure (CPAP) on glycemic measures in patients with type 2 diabetes (T2D) remains unclear. We aimed to determine whether CPAP treatment of OSA improves glycemic measures in patients with T2D. METHODS: This randomized controlled trial (N = 98) examined changes in glycemic measures following 12 weeks of active (n = 49) or sham (n = 49) CPAP and consideried participants' adherence to CPAP therapy (percentage of days with ≥4 hours use and average hours/day of use). RESULTS: Baseline treatment groups were similar. Regarding the efficacy of active vs sham-CPAP over time, at 6 weeks, both groups had similar reductions in fructosamine (mean difference [MD], 95% confidence interval [CI]: CPAP -13.10 [-25.49 to -0.7] vs. sham -7.26 [-20.2 to 5.69]; P = .519) but different in HbA1c (CPAP -0.24 [-0.48 to -0.003] vs sham 0.15 [-0.10 to 0.4]; P = .027). At 12 weeks, reductions in HbA1c values were similar by group (CPAP -0.26 [-0.53 to 0.002] vs sham -0.24 [-0.53 to 0.04]; P = .924). HbA1c reductions were associated with a greater percentage of cumulative days of CPAP usage ≥4 hours per day (b [SE] = 0.006 [0.002]; P = .013) and cumulative hours of CPAP use (b [SE] = 0.08 [0.08]; P = .012). CPAP use of ≥7 hours was associated with a significant reduction in HbA1c (b [SE] 0.54 [0.16]; P = .0012). CONCLUSION: CPAP treatment of OSA did not result in sustained improved glycemic control compared to sham in the intent-to-treat analysis. CPAP adherence was associated with greater improvements in glycemic control.