Increased compliance with continuous positive airway pressure (CPAP) may reduce the risk for the development of diabetic retinopathy in patients with type 2 diabetes who have obstructive sleep apnea (OSA), according to the results of a retrospective, cross-sectional study published in Optometry and Vision Science.

Investigators sought to compare the prevalence of diabetic retinopathy in patients with type 2 diabetes and OSA who were compliant with CPAP therapy vs those who were not CPAP-compliant. Eligible participants were seen at the Pulmonary and Eye Clinics at Veterans Affairs Maine between 2011 and 2016 to monitor them for CPAP compliance and diabetic retinopathy within a 12-month period. If multiple visits took place during the study period, the most recent set of visits was used for data compilation. For all participants, average CPAP wear time, percentage of nights the CPAP appliance was worn, and treated apnea-hypopnea index were obtained from CPAP smart card data from individuals with diabetes who visited the clinic.

Among a total of 1771 patient charts that were reviewed, 321 met study inclusion criteria. Of these, 19.6% (63 of 321) had diabetic retinopathy and 80.4% (258 of 321) did not have retinopathy. Among the participants in the retinopathy group, 51 had mild nonproliferative disease, 7 had moderate nonproliferative disease, 2 had severe nonproliferative disease, and 3 had proliferative diabetic retinopathy. Overall, 9 patients had diabetic macular edema.

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“The prevalence rates of diabetic retinopathy in the [CPAP]-compliant group and the noncompliant group were 16.1 and 26.1%, respectively,” the authors wrote. Patients in the CPAP group were significantly less likely to have diabetic retinopathy (odds ratio, 0.54; 95% CI, 0.31-0.94; P =.04). The relationship between CPAP compliance and diabetic retinopathy remained statistically significant even after adjusting for other factors known to increase the likelihood of diabetic retinopathy, including duration of diabetes and hemoglobin A1C level.

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The investigators concluded that the findings from the current study provide additional evidence regarding the beneficial effects of CPAP use for the management of OSA-related comorbidities in patients with type 2 diabetes.


Smith JP, Cyr LG, Dowd LK, Duchin KS, Lenihan PA, Sprague J. The Veterans Affairs continuous positive airway pressure use and diabetic retinopathy study. Optom Vis Sci. 2019;96(11):874-878.