The severity of this type of nerve damage -- called diabetic peripheral neuropathy -- is linked with the extent of sleep apnea and the degree of low blood oxygen levels that occur while patients sleep, the researchers found.
People with obstructive sleep apnea subconsciously awaken many times a night -- even dozens of times an hour -- because their airways close, disrupting their breathing. Those with diabetic peripheral neuropathy may have numbness or tingling in their extremities, or damage to their major organs.
The study of 234 adults with type 2 diabetes found that sleep apnea was independently associated with diabetic peripheral neuropathy even after the researchers accounted for a number of other possible factors, including obesity, ethnicity, gender, age at diabetes diagnosis, and the length of time a person had diabetes.
"Obstructive sleep apnea is known to be associated with inflammation and oxidative stress, so we hypothesized that it would be associated with peripheral neuropathy in patients with type 2 diabetes," lead author Dr. Abd Tahrani, a clinical lecturer in endocrinology and diabetes at the University of Birmingham in England, said in a news release from the American Thoracic Society.
However, while the study uncovered an association between obstructive sleep apnea and peripheral neuropathy in diabetic patients, it did not prove a cause-and-effect relationship.
Further research is needed to determine the role of sleep apnea and low blood oxygen levels in the development and progression of nerve damage in patients with type 2 diabetes, and to assess the potential impact of continuous positive airway pressure treatment on diabetic peripheral neuropathy, the study authors said.
Continuous positive airway pressure treatment, or CPAP, keeps obstructive sleep apnea patients' airways open while they sleep.