Most children with type 1 diabetes have a drop in the blood sugar during exercise. This drop in the blood sugar can result in hypoglycemia (low blood sugar). In children using an insulin pump, there is an opportunity to reduce the basal insulin rate during exercise. This study is being conducted to determine if decreasing the insulin that is received during exercise will reduce the risk of hypoglycemia. We hope to learn more about how the body responds to hypoglycemia and to hyperglycemia (high blood sugar) when it occurs.