Aims: To clarify the relationship between obstructive sleep apnoea (OSA) and diabetic retinopathy.
Research design and methods: A cohort of 240 men from primary and secondary care previously participated in a study on the prevalence of OSA in Type 2 diabetes and provided anthropometric information, details of their diabetes, had glycated haemoglobin (HbA1c) measured and overnight oximetry performed. They were re-contacted for permission to review their routine screening clinical retinal photographs, which were then scored by a trained grader, providing detailed retinopathy, maculopathy and photocoagulation scores.
Results: One hundred and eighteen men both consented and had retinal photographs available to review. Of these, 24% had OSA, with mean+/-sd 4% oxygen saturation (SaO2) dips/h of 20.9+/-16.6 vs. 2.8+/-2.1 in the non-OSA group. As expected, the OSA group had a significantly higher mean body mass index of 31.9+/-5.2 vs. 28.5+/-5.1 kg/m2 and neck size 44.5+/-3.6 vs. 41.9+/-2.5 cm, but the two groups did not differ significantly in age, diabetes duration, diabetes treatment, HbA1c, smoking history or proportion with known hypertension. Retinopathy and maculopathy scores were significantly worse in the OSA group (P<0.0001). Multiple regression analysis showed only OSA (R2=0.19, P<0.0001) and HbA1c (R2=0.04, P=0.03) to be significant independent predictors of retinopathy. OSA was the only independent significant predictor of the total microaneurysm score (R2=0.21, P=0.004), a detailed retinopathy subclassification. OSA was the only independent significant predictor of maculopathy (R2=0.3, P<0.001).
Conclusion: In men with Type 2 diabetes, there is a strong association between retinopathy and OSA, independent of conventional retinopathy risk factors.