Inverse cross-sectional and longitudinal relations between diabetic retinopathy and obstructive sleep apnea in type 2 diabetes: results from a national screening program.

Abstract Purpose In previous smaller studies, associations have been demonstrated between diabetic retinopathy (DR) and obstructive sleep apnea (OSA), but longitudinal relations have not been evaluated in larger cohorts. The aim of the present study was to assess the cross-sectional and prospective associations between DR and OSA in a national cohort of patients with type 2 diabetes. Design Cross-sectional and 5-year longitudinal registry-based cohort study. Participants and Controls:For cases, we included 153,238 patients with type 2 diabetes, who had attended diabetic eye screening and were registered in DiaBase. Each of these were matched by five control persons without diabetes of the same age and gender (n=746,148). Methods Data of exposure and outcome as well as systemic morbidity and use of medications were identified in national registers including the Danish Registry of Diabetic Retinopathy (DiaBase), the Danish National Patient Register, the Danish National Prescription Registry, and the Danish Civil Registration System. The index date was defined as the date of the first DR screening registered in DiaBase. Main Outcome Measures:Exposure was defined as present and level-specific DR, and main outcomes were crude, age- and sex-adjusted, and multivariable adjusted odds ratio (OR) for prevalent OSA as well as hazard ratios (HR) for 5-year incident OSA and DR. Results Patients with type 2 diabetes were independently more likely to have prevalent OSA (OR 2.01, 95% CI 1.95-2.08) and to develop OSA within five years (HR 1.55, 95% CI 1.46-1.64). Type 2 diabetic patients with DR at baseline were less likely to have prevalent (OR 0.57, 95% CI 0.52-0.62) and to develop incident OSA (HR 0.86, 95% CI 0.74-0.99). Likewise, patients with OSA had a lower risk develop HR (HR 0.83, 95% CI 0.74-0.92). Conclusions In a registry-based national cohort study, patients with type 2 diabetes had a higher risk of OSA. However, a 43% decreased risk of prevalent OSA was demonstrated in patients with DR, and prospectively OSA and DR were both inversely related with each other.