This is a pilot study to examine the short-term effects of supervised exercise on metabolic risk factors for type 2 diabetes mellitus in children from a population that is at high risk for this disease. We hypothesize that exercise 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:

1. Insulin resistance will be most evident in overweight children while an impaired ability of the pancreas to release insulin will be most evident in children with a family history of type 2 diabetes mellitus.
2. Exercise will significantly improve insulin resistance (as measured by the fasting glucose/insulin ratio) with little or no effect on insulin secretory capacity (as measured by circulating insulin concentration at 1, 3, and 5 minutes following an intravenous glucose load) in children.
3. Participation in a school-based health, nutrition, and exercise education program will have long-term beneficial effects on health-related behaviors and on insulin resistance.

Early adolescent