The decline in blood glucose levels is less with intermittent high-intensity compared with moderate exercise in individuals with type 1 diabetes

OBJECTIVE - To compare the response of blood glucose levels to intermittent high-intensity exercise (IHE) and moderate-intensity exercise (MOD) in individuals with type 1 diabetes.RESEARCH DESIGN AND METHODS - Seven healthy individuals with type 1 diabetes were tested on two separate occasions, during which either a 30-min MOD or IHE protocol was performed. MOD consisted of continuous exercise at 40% V-O2peak, while the IHE protocol involved a combination of continuous exercise at 40%V-O2peak, interspersed with 4-s sprints performed every 2 min to simulate the activity patterns of team sports.RESULTS - Both exercise protocols resulted in a decline in blood glucose levels. However, the decline was greater with MOD (-4.4 ± 1.2 mmolA) compared with IHE (-2.9 ± 0.8 mmolA; P < 0.05), despite the performance of a greater amount of total work with IHE (P < 0.05). During 60 min of recovery from exercise, glucose levels remained higher in IHE compared with MOD (P < 0.05). Furthermore, glucose levels remained stable during recovery from IHE, while they continued to decrease after MOD (P < 0.05). The stabilization of blood glucose levels with IHE was associated with elevated levels of lactate, catecholamines, and growth hormone during early recovery from exercise (P < 0.05). There were no differences in free insulin, glucagon, cortisol, or free fatty acids between MOD and IHE.CONCLUSIONS - The decline in blood glucose levels is less with IHE compared with MOD during both exercise and recovery in individuals with type 1 diabetes.