OSA, the most common form of sleep-disordered breathing, is characterized by recurrent collapse of the upper airway during sleep leading to periods of intermittent hypoxia and sleep fragmentation. There is growing evidence that OSA is associated with metabolic abnormalities and may be implicated in causality of metabolic disorders. OSA is linked to increased risk of hypertension, insulin resistance, glucose intolerance and type 2 diabetes, dyslipidemia, atherosclerosis, and non-alcoholic fatty liver disease, independent of underlying obesity. There are interactions between metabolic dysregulation and OSA that may lead to a vicious circle of cardiovascular and metabolic morbidity. The complexity of the relationship between metabolism and OSA can be scrutinized most effectively with animal models, which can account for all possible confounding factors.