This study examines risk factors for type 2 diabetes in children representing multiple discrete ethnic groups. It also examines the short term effects of school-based health education supervised exercise on metabolic risk factors for type 2 diabetes mellitus in children. The investigators hypothesize that exercise and health education will significantly improve insulin sensitivity in all children, especially in children who are already insulin resistant, thereby lowering the risk that they will go on to develop type 2 diabetes mellitus. The specific hypotheses being tested are: