Lower Blood Pressure Linked to CPAP Adherence in Those With OSA and Type 2 Diabetes

Investigators identified a potential dose-response relationship between lower systolic blood pressure and rate CPAP-adherence rates in those with both OSA and type 2 diabetes.

Continuous positive airway pressure (CPAP) adherence is significantly associated with lower diastolic blood pressure (DBP) and systolic blood pressure (SPB) in patients with both type 2 diabetes and obstructive sleep apnea (OSA), a recent study found. Investigators further concluded that lower SBP was associated with greater CPAP use in the CPAP-adherent patient population. 

The retrospective study reviewed medical records of 1295 patients with type 2 diabetes diagnosed with OSA between 2010 and 2017, with 578 participants providing enough data for follow-up evaluation. Those that were CPAP-adherent (n = 260; 45.0%) recorded significantly lower SBP (ß = –1.95 mm Hg; P = .001) and DBP (ß = –2.33 mm Hg; P <.0001), when compared with patients that were CPAP nonadherent (n = 318; 55.0%). The mean ages were 55.4 years for CPAP-adherent and 54.9 years for CPAP-nonadherent groups.1 

When adjusted for age at polysomnography (PSG), sex, body mass index, baseline SPB, and the amount of hypertension medications taken, investigators found significant association between CPAP-adherent patients, who had 17% greater adherence, and a 2-mm-Hg lower SBP, indicating the potential for a dose-response relationship. 

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“Our findings concerning blood pressure confirm results from studies in the general population, with a similar effect size. In a meta-analysis of 7 RCTs, CPAP use, compared to no CPAP or sham CPAP, was associated with significant reductions in 24-hour ambulatory SBP of 2.32 mm Hg and DBP of 1.98 mm Hg, with more significant improvement in nocturnal SBP than in diurnal SBP,” study coauthor Bharati Prasad, MD, MS, assistant professor, department of medicine, University of Illinois at Chicago College of Pharmacy, et al wrote.1 “The magnitude of reduction in blood pressure in our study is clinically significant as the data from the Framingham Heart Study revealed that a 2 mm Hg lower DBP was associated with a 15% reduction in cerebrovascular accident and transient ischemic attacks.”

Patients in the CPAP-nonadherent group data generally were more likely to be taking anti-hypertensive agents when compared to the CPAP-adherent group, at 93.4% vs 88.2%, respectively (P = .04), and were also more likely to be taking insulin than CPAP-adherent patients, at a rate of 62.9% vs 51.6%, respectively (P = .01). 

The average follow-up was 2.5 years, investigators noted, and within the CPAP-adherent group, high-density lipoprotein (HDL) levels were more likely to be higher (+3.34 mg/dL; P = .06; 283 HDL measurements) triglycerides (TG) were more likely to be lower (–0.16 mg/dL [log]; P = .07; 242 TG measurements), compared to the CPAP-nonadherent group. 

No significant differences were identified in estimated glomerular filtration rate, cholesterol, hemoglobin A1c, or incident cardiovascular disease (CVD)/peripheral vascular disease/ cerebrovascular events between the CPAP-adherent and nonadherent groups. Limitations of the study included the retrospective design, as well as the fact that CPAP adherence data was specific to patients’ first visits, with some patients diagnosed with OSA not showing recorded CPAP data.

Another recent study evaluated the relationship between preexisting diabetes, CVD, diabetes, and intermittent hypoxemia (IH) found that IH was more severe in patients who had preexisting CVD at baseline, and preexisting diabetes and CVD were associated with worsening of IH. 

A higher oxygen desaturation index (ODI) (β = 1.77 [95% CI, 0.41-3.13]; P = .011), desaturation severity (β = 0.07 [95% CI, 0.00-0.14]; P = .048), and desaturation duration (β = 1.50 [95% CI, 0.31-2.69]; P = .013) were found in patients with preexisting CVD at baseline. Additionally, increased ODI (β = 3.59 [95% CI, 1.78-5.39]; P <.001), desaturation severity (β = 0.08 [95% CI, 0.02-0.14]; P = .015), and desaturation duration (β = 2.60 [95% CI, 1.22-3.98]; P <.001) was found in patients with diabetes during follow-up. Lastly, data showed increased ODI (β = 2.73, [95% CI, 1.15-4.32]; P = 0.001) and desaturation duration (β = 1.85 [95% CI, 0.62-3.08]; P = .003) in patients with CVD.2

Utilizing data from the Sleep Heart Health Study of patients US patients between 1995 and 2006, investigators concluded that IH was an essential consequence of sleep apnea (SA), indicating that patients would benefit from lifestyle counseling or treatment for SA to prevent future related comorbidities or adverse effects. 

REFERENCES
1. Sheth U, Monson RS, Prasad B, et al. Association of continuous positive airway pressure adherence with complications in patients with type 2 diabetes and obstructive sleep apnea. J Clin Sleep Med. Published online August 1, 2021. doi:10.5664/jcsm.9248
2. Karhu T, Myllymaa S, Nikkonen S, et al. Diabetes and cardiovascular diseases are associated with the worsening of intermittent hypoxaemia. J Sleep Res. Published online August 10, 2021. doi:10.1111/jsr.13441