Exercise and Type 2 Diabetes in Youth

Abstract

The antecedents of adult cardiovascular disease begin in childhood. Accompanying the dramatic increase in childhood obesity and decline in physical activity, the prevalence of type 2 diabetes mellitus (T2DM) in pediatrics is also rising, forecasting earlier macrovascular and microvascular complications. Poor physical fitness is associated with increased cardiovascular morbidity and mortality. The presence of T2DM appears to confer a specific exercise defect, as adults with T2DM have reduced VO(2)max, slower VO2kinetics, and slower heart rate kinetics when compared with age, pubertal stage, weight, and activity-matched controls. As little exercise data exists in youth with T2DM, our group assessed VO(2)max in adolescents with T2DM, compared with nondiabetic, obese, and lean controls. We found significant impairments in maximal and submaximal exercise, not explainable by weight or activity level alone. VO(2)max/kg was strongly related to insulin resistance, as well as inflammation, impaired endothelial function, and ectopic lipid deposition. Notably, these defects are already happening in very young patients, with no other comorbidities or reasons for exercise dysfunction. Therefore, since exercise capacity predicts cardiovascular and all cause mortality, it is critical to further assess the mechanisms of exercise dysfunction in T2DM youth, as well as the impact of diabetes treatments in adolescents. On the basis of studies in adults and in adolescents with obesity and insulin resistance, exercise interventions appear helpful, but further study in pediatric T2DM is required.