Exercise is generally recommended for individuals with type 1 diabetes because it is associated with numerous physiological (1,2) and psychological (3,4) benefits. However, participation in exercise can also increase the risk of experiencing severe hypoglycemia, during both exercise (5) and recovery (6). Unfortunately, there are no evidence-based guidelines for safe participation in intermittent high-intensity exercise (IHE), which characterizes most team and field sports, manual labor occupations, and spontaneous play in children. This is because the response of blood glucose levels to this type of exercise is not known, as previous research on intermittent exercise has employed exercise protocols that do not accurately reflect the high-intensity work–to–recovery ratios observed in intermittent sports (7,8). Therefore, the aim of this study was to investigate the effect of IHE that simulates the high-intensity work–to–recovery ratios observed in intermittent sports on blood glucose levels and glucoregulatory hormones in individuals with type 1 diabetes in order to assess the risk of hypoglycemia. Eight volunteers with type 1 diabetes (aged [±SD] 18.6 ± 2.1 years, BMI 22.1 ± 1.5 kg/m2, V o2peak 42.4 ± 7.3 ml · kg−1 · min−1, type 1 diabetes duration 7.0 ± 4.6 years, and HbA1c 7.0 ± 0.4%), who were free of complications and not taking …