Do you snore? Do you often feel tired even after a full night’s sleep? If so, you may have sleep apnea — a sleep disorder in which breathing is shallow or repeatedly interrupted, resulting in chronic sleep deprivation. The most common type of this sleep disorder is obstructive sleep apnea (OSA), often associated with loud snoring and caused by the blocking of air by the relaxed soft tissue in the back of the throat during sleep.
OSA has been linked to serious health problems, including diabetes. A study conducted by U of T researcher and recent graduate Dr. Tetyana Kendzerska and her colleagues found that among patients with OSA, initial severity of the disorder predicted the subsequent risk for developing incident diabetes.
“There is emerging evidence that OSA, through chronic intermittent hypoxemia (low oxygen level during sleep), recurrent arousals, and neurohumoral changes, may cause metabolic disturbances including insulin resistance, independently of other known risk factors,” Kendzerska says, explaining the relationship between sleep apnea and diabetes.
Participants underwent a diagnostic sleep study involving a technique called polysomnography (PSG), which is commonly used to detect sleep disorders. PSG records several physiological parameters and physical activities as participants sleep.
“[PSG] consists of electroencephalogram, electrooculogram, chin and anterior tibialis muscle electromyogram, oronasal manometry, chest and abdominal wall movements, hemoglobin saturation, snoring recordings, body position, and video monitoring during sleep,” Kendzerska says.
Using clinical and provincial health administrative data, the researchers conducted a historical cohort study to examine the occurrences of diabetes in an adult population with suspected OSA but who were initially non-diabetic. Between the years 1994 and 2010, 8,678 patients participated in a diagnostic sleep study at St. Michael’s Hospital, where researchers collected data on sleep apnea severity and physiological indicators, as well as demographic and clinical information. During a median follow-up period of 67 months, 11.7 per cent of patients developed diabetes.
“Apnea-hypopnea index (AHI), recorded by PSG, reflects the number of breathing interruption[s] during sleep and is used to diagnose sleep apnea and to assess this disease severity,” says Kendzerska, adding that severe OSA can be defined as having an AHI of more than 30 events per hour.
“Exploring the effect of age on the association between OSA and incident diabetes, we found decreased effect of AHI with age on incident diabetes indicating the importance of early detection of sleep apnea among young adults,” says Kendzerska.
She adds, “Identifying and treating OSA in patients may be a worthwhile strategy to reduce the risk of developing diabetes later in life, particularly in those with other known risk factors like obesity.”
