There is a high prevalence of obstructive sleep apnea in people with type 2 diabetes and abnormal glucose metabolism.
The International Diabetes Federation (IDF) Taskforce on Epidemiology and Prevention convened a Working Group in February 2007 to review the effect of diabetes on OSA. Polysomnography testing showed OSA in up to 9% of women and 24% of men with diabetes. There has long been a recognized association between type 2 diabetes and OSA, and there is emerging evidence that this relationship is likely to be at least partially independent of adiposity. Cross-sectional estimates from clinic populations and population studies suggest that up to 40% of patients with OSA will have diabetes.
Two large studies with clinic-based sample sizes of 250–300 subjects both demonstrated a positive association, independent of obesity, between the severity of OSA and indexes of insulin resistance determined by fasting insulin and glucose. Insulin resistance is a central part of the metabolic syndrome. The metabolic syndrome has many features in common with OSA including obesity, hyperlipidemia, hypertension and insulin resistance. OSA is so interwoven in the fabric of the metabolic syndrome, or Syndrome X, that the combination of OSA and metabolic syndrome has been labeled “Syndrome Z.”
Scientists reported that the pro-inflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNFalpha) were elevated in patients with disorders of excessive daytime sleepiness (EDS) and proposed that these cytokines were mediators of daytime sleepiness. They also reported that IL-6, TNFalpha, and insulin levels were elevated in sleep apnea independently of obesity.
The prevalence of metabolic syndrome in the US population, from the Third National Health and Nutrition Examination Survey (1988-1994), parallels the prevalence of symptomatic sleep apnea. This supports the hypothesis that cytokines and insulin resistance are mediators of EDS and sleep apnea in humans.
Sleep Apnea Secondary to Service-Connected Stroke and Ischemic Heart Disease
Obstructive sleep apnea (OSA) is characterized by repetitive interruption of ventilation during sleep caused by collapse of the pharyngeal airway. A recent meta-analysis that combined the results from nine prospective cohort studies reported that OSA was significantly associated with stroke in participants without previous cardiovascular disease.
Compared with the general population, patients with stroke or ischemic heart disease (IHD) have 3 to 4 times higher prevalence of OSA, approximately 60% to 70%. Stern, et al. found that OSA is present in up to 72% of ischemic and hemorrhagic stroke and TIA patients. The OSA was primarily obstructive in nature, with only 7% of patients having primarily central apneas. The OSA frequency was high in stroke patients despite a relatively low average BMI of 26.4 kg/m2.
It is most likely that the cause of sleep apnea in stroke victims is aberration in REM sleep. In Causes of Excessive Daytime Sleepiness in Patients with Acute Stroke-A Polysomnographic Study, Klobučníková et al. reported that See comment in PubMed Commons belowsleep disorders are common in stroke patients. Sleep-disordered breathing (SDB), which is present in up to 72% of stroke patients, is the most frequent cause of excessive daytime sleepiness (EDS) in the common population. 102 patients with the clinical diagnosis of acute stroke were enrolled into the study. EDS was present in 21 patients (20.6%). It was found that in a population with EDS, there is a significantly higher number of obstructive apneic pauses, central apneic pauses, as well as significantly higher values of respiratory disturbance index (RDI), RDI during non-rapid eye movement sleep, desaturation index, and significant decrease of REM sleep duration.