Sleep apnea linked to worsening diabetic eye disease

LONDON: People with both sleep apnea and type 2 diabetes have more than double the risk of worsening retina disease compared to diabetics without the sleep breathing disorder, a UK study suggests.

Researchers followed adults with type 2 diabetes over about four years and found that for those with milder eye disease at the start, having sleep apnea was linked to higher odds that it would become more advanced.

At the outset of the study, they also found that advanced “sight-threatening diabetic retinopathy” was already present in 43 percent of people with sleep apnea, compared to just 24 percent of those without apnea.

“Patients with type 2 diabetes and obstructive sleep apnea (OSA) are at increased risk of developing advanced retinopathy and also are at increased risk of greater decline in kidney function, as we found in a previous publication,” senior study author Dr. Abd A. Tahrani from University of Birmingham told Reuters Health.

“Hence, diagnosing OSA offers the opportunity to identify a high-risk group of patients which will allow doctors to apply preventative treatment strategy to slow the progression of these complications,” Tahrani said by email.

Diabetic eye disease, or retinopathy, affects as many as 50 percent of people with diabetes, yet it remains unclear exactly what contributes to its development or what causes it to get worse.

Past studies have found a link between sleep apnea and damage to tiny blood vessels that causes kidney and nerve problems in people with diabetes, the authors note.

Tahrani’s team looked at whether sleep apnea is associated with the progression of diabetic retinopathy in 230 patients with type 2 diabetes, none of whom had diagnosed respiratory conditions, including sleep apnea, at the start of the study.

After sleep monitoring was done, 63 percent of the participants were found to have obstructive sleep apnea.

At the outset, the rates of sight-threatening diabetic retinopathy, advanced diabetic retinopathy and maculopathy (damage to the part of the eye responsible for central vision) were already higher in patients with sleep apnea than in those without sleep apnea.

As time went on, three times as many patients with sleep apnea, 18.4 percent, progressed to more advanced stages of diabetic retinopathy compared to 6.1 percent of those without sleep apnea, according to the report in American Journal of Respiratory and Critical Care Medicine.

The worse the sleep apnea, the faster the progression of diabetic retinopathy, researchers found.

Sleep apnea, however, did not appear to be associated with faster progression of existing sight-threatening diabetic retinopathy or maculopathy.

On a positive note, sleep apnea treatment with CPAP (continuous positive airway pressure) slowed the progression to advanced diabetic retinopathy.

“While the impact of CPAP on retinopathy and other diabetes-related complications requires further study, CPAP treatment has several benefits, including lowering the blood pressure, improving sleepiness, improving quality of life, improving OSA-related symptoms and reducing the risk of road traffic accidents; hence CPAP treatment should be considered in patients with type 2 diabetes who have OSA,” Tahrani said.

“Diabetic retinopathy is mostly caused by diabetes, and more severe diabetic retinopathy could be promoted by poor blood sugar control and OSA in type 2 diabetes,” said Dr. Gen-Min Lin from Hualien-Armed Forces General Hospital and National Dong Hwa University in Hualien, Taiwan, who recently looked at the association of sleep apnea with changes in the tiny blood vessels of the retina.

“In some cross-sectional studies, women with more severe OSA were found to have higher risk of less severe diabetic retinopathy (such as microaneurysms) than men,” Lin told Reuters Health in an email. “This sex difference might be related to female sex hormone or higher grade inflammation status in women.”