[Truncated abstract] Exercise is generally recommended for individuals with type 1 diabetes mellitus since it is associated with numerous physiological and psychological benefits. However, participation in exercise can also increase the risk of experiencing severe hypoglycaemia both during exercise and recovery. Unfortunately, existing guidelines to minimise the risk of exercise-induced hypoglycaemia are often general and fail to take into account that different precautions are required for exercise of varying type, duration and intensity. Specifically, there are no evidence-based guidelines for safe participation in intermittent high-intensity exercise (IHE), which characterises the activity patterns of most team and field sports, manual labour occupations and spontaneous play in children. This is because the response of blood glucose levels to this type of exercise is not known. Consequently, the purpose of this thesis was to investigate the glucoregulatory responses to IHE that replicates the high-intensity work-to-recovery ratios observed in intermittent sports in individuals with type 1 diabetes, in order to assess the associated risk of hypoglycaemia. The first study of this thesis examined the effect of the repeated bouts of high-intensity exercise that characterise IHE compared to remaining inactive, on blood glucose and glucoregulatory hormone levels in individuals with type 1 diabetes. Eight healthy individuals with type 1 diabetes were tested on two separate occasions during which either a 20 minute rest (CON) or an IHE protocol designed to simulate the activity patterns of team sports was performed (repeated 4 second sprints every 2 minutes). ... During the second hour of recovery, Ra and Rd returned to baseline following MOD, but remained elevated after IHE. These changes in Ra and Rd were consistent with a lower glucose infusion rate (GIR) during early recovery from IHE and a higher GIR after 2 hours of recovery compared to MOD. In conclusion, the repeated bouts of high-intensity exercise associated with IHE stimulate a more rapid and greater increment in Ra during exercise and attenuate glucose Rd during early recovery. These findings assist in explaining, in part, the previous observation that the risk of hypoglycaemia might be lower during IHE and early recovery compared to MOD. Overall, the findings of this thesis have implications for current recommendations aimed at managing blood glucose levels during and after exercise to avoid hypoglycaemia.