The Connection Between Sleep Apnea and Poor Glycemic Control in Patients with Type 2 Diabetes
It’s well known in the medical field that obstructive sleep apnea (OSA) is an independent risk factor for developing type 2 diabetes. However, it’s unclear if OSA severity has an effect on glycemic control in patients who have type 2 diabetes.
Researchers from the United Kingdom set out to study this, and their results were published in the September 2011 issue of Diabetes Technology & Therapeutics in an article called “Effects of sleep apnea severity on glycemic control in patients with type 2 diabetes prior to continuous positive airway pressure treatment.”
In their observational cross-sectional study, the researchers set out to investigate the connection between OSA severity and glycosylated hemoglobin (HbA1c) in patients who have type 2 diabetes. This study included 52 patients who had type 2 diabetes and who also had risk factors for OSA. These patients underwent polysomnography, and they completed a questionnaire that recorded personal data, including their medical history, lifestyle, and demographics.
HbA1c and liver transaminase (LT) levels, the severity and occurrence of OSA, daytime sleepiness, and insulin dose were also examined. The prevalence of OSA in the cohort was 58%—stratified as mild, moderate, and severe.
Researchers adjusted for age, gender, BMI, diabetes duration, and insulin dose; they found that increasing HbA1c levels (p<0.014 for linear trend) were associated with OSA severity but not with daytime sleepiness. Mean HbA1c values were 8.62% for those who did not have OSA, 9.36% for mild OSA, 10.61% for moderate OSA, and 9.91% for severe OSA.
No noteworthy associations were seen between LT levels with OSA severity (p=0.324), BMI with OSA severity (p=0.278), or HbA1c levels with the Epworth Score (daytime sleepiness measure) (p=0.46).
The study provides evidence that OSA severity is independently associated with poor glycemic control, notably reaching a plateau when going from moderate OSA to severe OSA. This was noteworthy even after adjusting for confounding factors (eg, insulin dose). Therefore, treating OSA in patients with type 2 diabetes may improve glycemic control.