Is sleep-disordered breathing an additional risk factor for the metabolic syndrome in obese children and adolescents?

Sleep-disordered breathing is highly prevalent in childhood obesity. Two recent cross-sectional studies have demonstrated an independent association between the severity of sleep-disordered breathing and the metabolic syndrome. A limited number of studies have also addressed the correlation between sleep-disordered breathing and insulin resistance, the core factor of the metabolic syndrome. Cross-sectional reports in modestly obese children are in favor of an association between sleep apnea and insulin resistance. However, these findings were not confirmed in studies of normal-weight children and of morbidly obese children. Only one out of three treatment studies before and after adenotonsillectomy confirmed the association between sleep apnea and insulin resistance, but only in obese children. Although statistical power issues and differences in patient characteristics might partially explain these contradicting results, the evidence to date is far from establishing a causal link between sleep-disordered breathing and insulin resistance. Longitudinal studies and randomized control trials are therefore warranted to investigate a possible causal link between sleep-disordered breathing and insulin resistance.