Rationale: The five-fold increase in prevalence of childhood obesity in Canada over the last 15 years has led to an increasing number of pediatric cases of obesity-related obstructive sleep apnea (OSA). Not only is the prevalence of OSA significantly higher among obese children compared with the general population, but in this group, routine treatment by adenotonsillectomy has a much lower cure rate. Instead, Positive Airway Pressure (PAP) treatment is usually prescribed. Other complications of obesity are also increasingly recognized in children, including metabolic disturbances with insulin resistance (IR). This is particularly concerning, since IR is an identified surrogate measure of future obesity-related sequelae, such as diabetes, dyslipidemia, cardiovascular disease (including hypertension, and heart rate disturbances), inflammation and impaired quality of life. Of particular interest, the IR related to obesity can be exacerbated by OSA and the severity of IR correlates with the severity of OSA. IR is measured using a homeostasis model assessment of insulin resistance (HOMA-IR) and is calculated from fasting blood glucose and insulin levels. In obese adults with OSA, HOMA-IR, as well as cardiovascular and other metabolic markers, has been shown to improve following PAP therapy. Such a study has not been done in children. We hypothesize that PAP treatment for obese children with moderate-severe OSA will improve markers of obesity-related disease.