Obstructive sleep apnea, retinopathy strongly linked in Type 2 diabetes
MedWire News: Retinopathy and obstructive sleep apnea (OSA) are strongly correlated in men with Type 2 diabetes, with the relationship being independent of conventional risk factors for retinopathy, UK researchers have shown.
Sophie West (Freeman Hospital, Newcastle-upon-Tyne) and co-authors say that their results, if confirmed, underline the importance of assessing diabetes patients for OSA and offering treatment where needed.
OSA is primarily caused by central obesity but is also associated with cardiometabolic abnormalities. In this study, West et al hypothesized that the episodes of intermittent hypoxia and blood-pressure surges seen in OSA could cause retinal damage and worsening of diabetic retinopathy.
They analyzed data on 240 men with Type 2 diabetes who had previously participated in a study into the prevalence of OSA in diabetes. As part of the study, the men underwent sleep studies and had retinal photographs taken and graded by two independent reviewers.
Nearly one-quarter (24%) of the men were found to have significant OSA, West et al report in the journal Diabetic Medicine. As expected, men with OSA had a significantly higher body mass index and neck size than those without the condition.
Interestingly, the OSA group also had significantly higher frequencies of retinopathy, maculopathy, and ophthalmic microaneurysms than the non-OSA group at 54% versus 31%, 29% versus 4%, and 26% versus 8%, respectively.
OSA was associated with a number of specific ophthalmic abnormalities, such as hemorrhages inside and outside the arcades, hemorrhages less than one disc in diameter from the fovea, hard exudates inside the arcades, and cotton wool spots inside the arcades.
Multiple regression analysis confirmed that OSA was a significant independent predictor for all measures of retinopathy and explained 19% of the variance; a further 4% was explained by levels of glycated hemoglobin.
Commenting, West and colleagues say that potential mechanisms linking OSA and retinopathy include recurrent episodes of intermittent hypoxia, reoxygenation, sympathetic surges, and increases in blood pressure. Importantly, it is not known whether treatment of OSA would delay the progression of retinopathy.
“If these results are confirmed by larger studies of this nature, it will emphasize the importance of identifying men with Type 2 diabetes who also have OSA,” the authors conclude.
“Patients with symptoms of OSA, such as loud snoring, witnessed apneas and excessive daytime sleepiness, should certainly be referred for sleep studies, if only for symptom relief.”
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By Joanna Lyford