Exercise is important in the management of type 1 diabetes mellitus (T1DM). Modern diabetes care includes the goal that all youth meet guidelines for regular physical activity. Evidence suggests regular physical activity improves cardiovascular health, lipid profiles, psychosocial wellbeing and, possibly, glycemic control in youth with T1DM. However, exercise is especially problematic for children and adolescents because wide glycemic excursions commonly occur during and after exercise and may increase the risk of severe hypoglycemia. In addition, youth with T1DM have abnormal counterregulatory hormone responses, further increasing the risk of exercise-associated hypoglycemia. Recent studies have demonstrated that this risk is present during, and many hours after exercise, and have tested strategies to prevent exercise-induced hypoglycemia in youth. Despite these recent studies, the fear of hypoglycemia remains a major impediment to achieving target glycemic control in youth, targets that have recently been tightened. Equally, data suggests fear of hypoglycemia is the major impediment to participation in regular daily exercise in T1DM. Recent advances in insulin delivery systems and in real time continuous glucose monitoring have improved care for youth with T1DM, allowing safer participation in exercise programs. The impending development and approval of "closed loop" insulin delivery systems (the artificial pancreas) holds great promise for the safe participation in exercise for all youth with T1DM.