Properly treating a common sleep-related breathing disorder may have benefits for the heart and for blood sugar, a new study suggests.
If people with obstructive sleep apnea don’t use machines at night to help keep the airway open, measures of their heart health and blood sugar worsen, researchers found.
“One of the long-standing debates in our field” is whether sleep apnea causes heart issues and problems with blood sugar “or if they’re just associated,” said the study’s senior author, Jonathan Jun of Johns Hopkins University.
In obstructive sleep apnea, the airway intermittently collapses or becomes blocked during sleep. The blocked airway causes pauses in breathing. Some people address this by using CPAP — continuous positive airway pressure — machines at night to keep the airway open.
In the past, researchers have tried to directly link sleep apnea with heart health and blood sugar by comparing patients instructed to use CPAP devices with patients instructed to sleep without these machines. But one of the major issues with those studies is that people may not actually use the CPAP machine, Jun said by phone.
For the new study, the researchers recruited 31 people with moderate to severe obstructive sleep apnea who were known to regularly use CPAP machines.
The participants slept two nights in a lab, using their CPAP device on only one of the nights. The researchers obtained blood samples while participants slept.
“We are looking at real-time changes,” Jun said. “We’re getting blood every 20 minutes.”
As reported in the Journal of Clinical Endocrinology and Metabolism, on the night without CPAP, patients’ obstructive sleep apnea returned. On those nights, the participants had low levels of oxygen in their blood, poor sleep and an increased heart rate.
Additionally, their blood samples showed increases in fatty acids, sugar and the stress hormone cortisol.
The researchers also saw increases in blood pressure and arterial stiffness, which has been linked with a risk for heart problems.
“These were obese patients and patients with relatively severe sleep apnea. They also had other medical problems,” Jun pointed out. People who fit that description may be experiencing the same changes if they sleep without using a CPAP machine, he said.
Glucose and fatty acids rose in the overall group without the CPAP machines, but participants with diabetes may be more vulnerable to the glucose elevation, Jun warned.
He said the study can’t say what would happen to people with milder sleep apnea.
Because obesity has been tied to an increased risk of sleep apnea, it has been difficult to know whether it’s sleep apnea or obesity that is causing those problems, Jun noted.
The new study, he said, “advances that idea that other conditions and not obesity itself are drivers of those levels.”