As obesity has become more prevalent, the incidence of type 2 diabetes mellitus in children and adolescents has also increased. Obesity during adolescence leads to an increased risk for disease and premature death during adulthood, independent of obesity during adulthood. Obesity is the major risk factor impacting insulin sensitivity. Subjects with insulin resistance are at risk for progression to diabetes. Type 2 diabetes mellitus in obese children and adolescents is frequently asymptomatic. It is essential to identify children at high risk who need aggressive lifestyle modification focused on weight reduction and increased physical activity. Early detection and therapy of obese children and adolescents with type 2 diabetes may reduce the risk of cardiometabolic consequences and other long-term complications in adulthood.