The long-term goals of our research are to understand the biochemical morbidity surrounding obstructive sleep apnea syndrome to define better the need for treatment and to determine modifiable risk factors for the disease. Our current hypothesis is that sleep-related hypoxemia results in alterations in metabolic regulatory peptides, specifically insulin and insulin-like growth factors (IGF-1 and IGF-2), which are known or suspected factors for obesity and disorders such as hypertension, glucose intolerance, and atherosclerosis. Surveys of clinic populations suggest a relationship between body habitus, parameters of sleep-disordered breathing, indices of oxygenation, and insulin resistance, defined by fasting serum levels of glucose and insulin. Results will provide insight into the role of metabolic regulatory peptides in the pathogenesis of sleep-disordered breathing and the mechanisms for this association.