Sleep Apnea Associated With Diabetic Retinopathy, Neuropathy

SAN DIEGO (EGMN)–Obstructive sleep apnea in patients with type 2 diabetes predicted a three- to fourfold higher risk for diabetic peripheral neuropathy or sight-threatening retinopathy, separate analyses have found.

The results suggest that obstructive sleep apnea may play a role in the development of peripheral neuropathy and sight-threatening retinopathy in people with diabetes, Dr. Abd Tahrani and his associates reported at the annual scientific sessions of the American Diabetes Association. Ongoing studies are exploring the possible mechanisms involved.

Further research also is warranted on the possibility that treating obstructive sleep apnea might affect the development or progression of retinopathy or neuropathy, added Dr. Tahrani of the University of Birmingham (U.K.), where he is a research fellow for the U.K. National Institute for Health Research.

The prospective studies recruited random patients from a hospital-based, outpatient diabetes clinic in the United Kingdom. Individuals were excluded if they had a known respiratory disorder, including obstructive sleep apnea. Patients had a mean age of 59 years and a mean 11-year history of diabetes, and 48% were white.

Participants underwent one night of home-based multichannel respiratory monitoring, and were considered to have obstructive sleep apnea if they had an apnea-hypopnea index of at least 5 events per hour.

In 224 patients who also were assessed for sight-threatening retinopathy, 63% had obstructive sleep apnea and 38% had sight-threatening retinopathy. Patients with obstructive sleep apnea were significantly more likely to have sight-threatening retinopathy (48%) than were patients without obstructive sleep apnea (20%).

The study defined sight-threatening retinopathy as the presence of preproliferative or proliferative retinopathy, maculopathy, or the need for laser treatment.

After adjustment for a wide range of possible confounders, patients with obstructive sleep apnea were 3.6 times more likely to have sight-threatening retinopathy, 5 times more likely to have advanced diabetic retinopathy, and 4.4 times more likely to have maculopathy than were patients without obstructive sleep apnea.

In a separate study by the same investigators involving 231 patients who were assessed for both obstructive sleep apnea and peripheral neuropathy, 65% had obstructive sleep apnea and 45% had diabetic peripheral neuropathy. Patients with obstructive sleep apnea reported more neuropathic symptoms.

Among patients with obstructive sleep apnea, 60% had diabetic peripheral neuropathy, compared with 27% of patients without sleep apnea.

Obstructive sleep apnea conferred a significant threefold higher risk for peripheral neuropathy after adjustment for a wide variety of potentially confounding variables, Dr. Tahrani reported. The severity of peripheral neuropathy correlated with the severity of obstructive sleep apnea.

Obstructive sleep apnea was prevalent in 75% and 52% of white and South Asian patients, respectively. Likewise, diabetic peripheral neuropathy was more prevalent in whites (56% vs. 40%). Both differences were significant.

The lower prevalence of obstructive sleep apnea in the South Asian patients might be one reason for the lower prevalence of diabetic peripheral neuropathy, the investigators suggested.

Dr. Tahrani reported having no conflicts of interest.

In comments provided during an interview at the meeting, Cheryl Tannas, R.N., a diabetes educator at the University of Michigan, Ann Arbor, said that “these two studies definitely are helpful to clinicians caring for patients with diabetes. The relationships these studies show between obstructive sleep apnea and retinopathy or neuropathy are not ones that have been reported previously.

“It makes a lot of sense to me that this would happen,” said Ms. Tannas, who is doing a doctoral dissertation on sleep disturbances in diabetes. She did not participate in either of these studies.

“Obstructive sleep apnea and type 2 diabetes complications share common mechanisms of oxidative stress and inflammation,” she noted. “The findings point to the significance of managing obstructive sleep apnea or any other sleep disorders. People need to take it much more seriously than they have.”

“All people with diabetes should be assessed for the quantity and quality of their sleep. In our area, some patients are assessed, and some are not. Some are assessed only for sleepiness, but in mild to moderate obstructive sleep apnea, they may not be sleepy, so that’s not a good indicator of risk,” said Ms. Tannas.

Copyright (c) 2010 Elsevier Global Medical News. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.