People who suffer from both Type 2 diabetes and undiagnosed obstructive sleep apnea (OSA) are at a greater risk of developing diabetic retinopathy, new research led by the University of Birmingham has found.

Previous studies had shown a link between OSA and diabetic retinopathy. However, prior to this new research, published in American Journal of Respiratory and Critical Care Medicine, there had been no published studies assessing the impact of OSA on the progression of diabetic retinopathy in patients with Type 2 diabetes.

Patients were assessed for diabetic retinopathy using retinal imaging, while OSA was assessed using a home-based cardio-respiratory device. Results showed that diabetic retinopathy prevalence was higher in patients with OSA (42.9%) compared to those without OSA (24.1%).

At follow-up appointments, on average 43 months later, the patients with OSA (18.4%) were more likely to develop moderate to severe diabetic retinopathy compared to those without OSA (6.1%).

The study also showed that patients who received treatment for OSA using a machine connected to a face mask that delivers pressure to prevent the blockage of the airways during sleep had a lower risk of developing advanced diabetic retinopathy compared to patients who did not receive the treatment.

Author of the study, doctor Abd Tahrani of the University of Birmingham's Institute of Metabolism and Systems Research, said: ‘We can conclude from this study that OSA is an independent predictor for the progression to moderate or severe diabetic retinopathy in patients with Type 2 diabetes.

‘Our findings are important because improved understanding of the pathogenesis of diabetic retinopathy is important in order to identify new treatments.’

Research was carried out at two diabetes clinics at hospitals in the Midlands and involved 230 patients with Type 2 diabetes.