[Pathophysiological links between obstructive sleep apnea syndrome and metabolic syndrome].

Obstructive sleep apnea (OSA) is a chronic disease characterized by repetitive partial or complete closure of the upper airway during sleep. OSA tends to be associated with components of metabolic syndrome sharing a common ground of metabolic changes with metabolic syndrome itself. Recent studies showed that subjects with OSA were 6-9 times more likely to have metabolic syndrome than subjects without OSA. Intermittent hypoxia and sleep fragmentation in OSA can initiate intermediary mechanisms (oxidative stress, neurohumoral changes, inflammation) leading to the components of metabolic syndrome. OSA has been suggested to be a novel risk factor, inside the metabolic syndrome, contributing to increased cardiovascular risk. Several studies report that continuous positive airway pressure (CPAP) treatment can reverse pathophysiological changes in OSA, increasing insulin sensitivity and reducing blood pressure. Recent evidences show that CPAP treatment reduces the risk of cardiovascular events and mortality in subjects with OSA. Some subjects with metabolic syndrome can be affected by undiagnosed OSA: CPAP treatment could significantly reduce cardiovascular risk in this subgroup of patients.