Carbohydrate Supplementation During Prolonged Aerobic Exercise for People Living with Type 1 Diabetes on Insulin Pump Therapy: The ExCarbs Study

Moderate intensity exercise increases hypoglycemia risk in individuals with type 1 diabetes. This thesis assessed carbohydrate and insulin strategies during 120-min fasted exercise (~45% VO2peak) in fifteen individuals with type 1 diabetes. The strategies performed in randomized crossover design included: 1) carbohydrates of 0.3 g/kg/hr; 2) 50% basal rate reduction 90-min pre-exercise; and 3) carbohydrates of 0.3 g/kg/hr and 50% basal rate reduction at exercise start. In arms 1, 2, and 3 the change in blood glucose was -2.7 3.4 mmol/L, -1.9 2.5 mmol/L, and 0.3 2.6 mmol/L, respectively. Arm 2 had a lower RER (0.79 0.04), increased ketones (0.4 0.3 mmol/L), increased fat oxidation (0.51 0.2 g/min), and increased glucagon (30.9 22.3 pg/mL) at exercise end, compared to arm 1 (all P < 0.05). All strategies had minimal hypoglycemia throughout exercise, with arm 2 having increased fat oxidation and improved counter-regulatory function.