Metabolic disorders associated with obstructive sleep apnea in adults.

The relationship between metabolic disorders and obstructive sleep apnea (OSA) is multidirectional. Obesity is recognized as the strongest risk factor for OSA. It is unknown whether metabolic syndrome and insulin resistance/type 2 diabetes mellitus contribute to the development or aggravation of OSA, although this is likely. Conversely, OSA may be a risk factor for metabolic disorders. Strong evidence suggests that OSA may increase the risk of developing insulin resistance, glucose intolerance and type 2 diabetes mellitus. OSA has also been associated with the development and/or aggravation of obesity, dyslipidemia, metabolic syndrome and nonalcoholic fatty liver disease - a liver manifestation of metabolic syndrome. In addition, metabolic disorders are confounding factors in OSA. Metabolic disorders and OSA share common intermediate pathogenic pathways, including alterations in autonomic nervous system regulation, increased inflammatory activity, and alterations in adipokine levels and endothelial dysfunction, which may be involved in the interplay between these conditions. Overall, this complexity makes it especially difficult to reveal and understand the links between OSA and metabolic and cardiovascular disorders. The International Diabetes Federation has recently published clinical practice recommendations suggesting that OSA patients should be routinely screened for markers of metabolic disturbance and cardiovascular risk, such as waist circumference, blood pressure, and fasting lipid and glucose levels. It also recommends that the possibility of OSA should be considered in the assessment of all patients with type 2 diabetes mellitus and metabolic syndrome.