Effect of Continuous Positive Airway Pressure Therapy on Cardiovascular Risk Factors in Patients with Type 2 Diabetes and Obstructive Sleep Apnea

Abstract

Few prospective intervention studies have examined the effect of continuous positive airway pressure (CPAP) therapy on cardiovascular disease (CVD) risk factors in diabetes. Our objective was to determine whether CPAP improves CVD risk factors in patients with type 2 diabetes and obstructive sleep apnea (OSA). This was a randomized parallel group intervention trial in an urban Australian community. Fifty-nine participants of the Fremantle Diabetes Study Phase II at high risk for OSA consented to confirmatory polysomnography followed by randomization to a 3-month CPAP intervention initiated early (<1 wk) or late (1-2 months). Patients were assessed before and 1 and 3 months after CPAP started. Tests for repeated measures were used to compare variables of interest over time. Forty-four patients (75%) completed the study. Their mean ± sd age was 66.1 ± 8.8 yr, and 61.4% were male. Completers and noncompleters had similar age, sex, diabetes duration, apnea-hypopnea index, and Epworth Sleepiness Scale (P ≥ 0.29). There were no differences in outcome between early and late randomization, and the data were pooled. The Epworth Sleepiness Scale decreased between entry and 1 month [-4.8 (-6.5 to -3.1), P < 0.001]. Blood pressure improved between entry and 3 months (from 149 ± 23/80 ± 12 to 140 ± 18/73 ± 13 mm Hg; P ≤ 0.007). Pulse rate declined within the first month [-6 (-10 to -2) beats/min, P = 0.002]. Glycemic control and serum lipids, which were mostly within recommended target ranges at entry, did not change. Three months of CPAP in community-based people with type 2 diabetes significantly decreased blood pressure and pulse rate but did not influence metabolic control.