Sleep-disordered breathing (SDB) is a common condition with prevalence estimates of 2-4% in the general population. Epidemiological data suggest that SDB is an independent risk factor for cardiovascular disease. Glucose intolerance and insulin resistance are also well-recognized risk factors for the development of cardiovascular disease. A number of recent clinic-based studies suggest that, independent of obesity, SDB may adversely affect glucose tolerance and insulin sensitivity. The purpose of this study was to systematically review the evidence for the link between SDB, glucose intolerance, and insulin resistance. A MEDLINE search for SDB and metabolic disorders was performed and 24 articles that met the inclusion criteria were identified. Population-based studies indicate that habitual snoring is independently associated with glucose intolerance and insulin resistance. Studies that have used objective measures of SDB (e.g. polysomnography) provide further support for an independent link between SDB, glucose intolerance, and insulin resistance. However, studies on the treatment of SDB with continuous positive airway pressure (CPAP) have yielded inconsistent results and overall do not reveal an improvement in the metabolic disturbance after treatment. Although population-based prospective data on the metabolic implications of SDB are still lacking, current data point to an independent association between SDB and impaired glucose homeostasis. Potential mediators of this association include altered adrenergic function, the direct effects of hypoxemia on glucose regulation, and release of proinflammatory cytokines that affect metabolism.
"A parallel increase in the severity of OSAS and the cardiovascular events has also been described. OSAS is often associated with cardiovascular risk factors, such as diabetes mellitus, hyperlipidemia and obesity . Untreated OSAS is also associated with dysglycemia, systemic inflammation, endothelial dysfunction, platelet activation, and other cardiovascular consequences such as cardiac arrhythmias especially atrial fibrillation (AF), coronary artery disease, asymptomatic early atherosclerosis, and silent brain infarction . "
[Show abstract][Hide abstract] ABSTRACT: Background
In patients with Obstructive sleep apnea (OSA), the risks of fatal and non-fatal cardiovascular diseases and coronary artery disease are increased and measuring carotid intima-media thickness (CIMT) can assess these complications.
Studying the effect of OSA syndrome in the carotid artery wall thickness as an indicator to cardiovascular complications, and the effect of CPAP on these changes.
Subjects and methods
Polysomnography (PSG) was done for 45 patients; 29 patients of them proved to have OSA, and 10 obese subjects with normal PSG were included as a control group. All of them had ultrasonographic assessment of CIMT. 17 patients with OSA used CPAP overnight for 6 months and the CIMT was remeasured.
29 were diagnosed with OSA (12 severe, 9 moderate and 8 mild OSA). There was a highly significant difference (p < 0.01) in CIMT between patient and control groups, and also between severe and mild OSA patients with non-significant difference (p > 0.05) between severe and moderate OSA. Regarding the different risk factors predispose to atherosclerosis, only factors related to OSA syndrome were correlated with CIMT. There was a highly significant reduction (p < 0.01) in CIMT after six months of CPAP usage.
CIMT as a marker of atherosclerosis is significantly increased in patients with OSA and the use of CPAP in those patients is very important not only for improving sleep efficiency but also for reducing cardiovascular complications associated with OSAS.
"Findings from epidemiological studies indicate that sleep apnea is independently associated with hypertension  and cardiovascular disease . A growing body of literature suggests that sleep apnea is associated with fasting hyperglycemia, insulin resistance, and DM . "
[Show abstract][Hide abstract] ABSTRACT: Sleep needs in adults are estimated to be 7 to 8 hours per night. During the last forty years, sleep duration has decreased by about 2 hours per night, as a result of our lifestyle, workload, social activities and access to technology. There are several social, economic and public health consequences due to chronic sleep deprivation. Current data suggests that sleep deprivation as well as poor quality of sleep have an impact on the incidence and prevalence of both obesity and type 2 diabetes. Screening for sleep disorders and obstructive sleep apnea (OSA) should be routinely performed in an increased number of patients, particularly those at high risk, i.e. obese, diabetic and hypertensive patients.
"There is significant evidence that OSA is independently associated with metabolic dysfunction, including dyslipidemia, insulin resistance, and overweight/obesity . The latter as well as other factors in OSA may contribute to sleep debt, repetitive hypoxemia, increased sympathetic tone, and indeed hypertension. "
[Show abstract][Hide abstract] ABSTRACT: OSA is characterized by the quintessential triad of intermittent apnea, hypoxia, and hypoxemia due to pharyngeal collapse. This paper highlights the upstream mechanisms that may trigger cognitive decline in OSA. Three interrelated steps underpin cognitive dysfunction in OSA patients. First, several risk factors upregulate peripheral inflammation; these crucial factors promote neuroinflammation, cerebrovascular endothelial dysfunction, and oxidative stress in OSA. Secondly, the neuroinflammation exerts negative impact globally on the CNS, and thirdly, important foci in the neocortex and brainstem are rendered inflamed and dysfunctional. A strong link is known to exist between neuroinflammation and neurodegeneration. A unique perspective delineated here underscores the importance of dysfunctional brainstem nuclei in etiopathogenesis of cognitive decline in OSA patients. Nucleus tractus solitarius (NTS) is the central integration hub for afferents from upper airway (somatosensory/gustatory), respiratory, gastrointestinal, cardiovascular (baroreceptor and chemoreceptor) and other systems. The NTS has an essential role in sympathetic and parasympathetic systems also; it projects to most key brain regions and modulates numerous physiological functions. Inflamed and dysfunctional NTS and other key brainstem nuclei may play a pivotal role in triggering memory and cognitive dysfunction in OSA. Attenuation of upstream factors and amelioration of the NTS dysfunction remain important challenges.
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