Effects of moderate-to-vigorous intensity physical activity on overnight and next-day hypoglycemia in active adolescents with type 1 diabetes

OBJECTIVE: Physical activity (PA) provides many benefits to adolescents with type 1 diabetes; however, these individuals tend to have lower fitness and PA levels than their disease-free counterparts. The purpose of this study was to examine the acute temporal associations between moderate-to-vigorous intensity PA (MVPA) and hypoglycemia (continuous glucose monitor [CGM] reading ≤70 mg/dL). RESEARCH DESIGN AND METHODS: Nineteen participants (53% females) 14-20 years old with type 1 diabetes were recruited. Participant fitness was evaluated via indirect calorimetry using a maximal exercise test; body composition was measured using air displacement plethysmography. An accelerometer was worn continuously (3-5 days) and acceleration data used to estimate MVPA (minutes per day). Blood glucose values were simultaneously tracked using CGM. Controlling for sex, percent body fat (¿), fitness, and concurrent MVPA, the likelihood of nighttime and next-day hypoglycemia due to MVPA was examined using logistic regression. RESULTS: Participants were of average fitness (females: 43.9 mL/kg/min; males: 49.8 mL/kg/min) and adiposity (females: 26.2%; males: 19.2%); 63.2% met the U.S. federal guideline of accumulating 60 min/day of MVPA. Hypoglycemia was 31% more likely in those who accumulated 30 min/day more MVPA in the previous afternoon than those with less (95% CI 1.05-1.63; P = 0.017). CONCLUSIONS: The results suggest that participating in afternoon MVPA increases the risk of overnight and next-day hypoglycemia, independent of sex, ¿, fitness, and concurrent MVPA. While promoting PA as a healthy behavior, it is important to educate adolescents with type 1 diabetes on prevention of hypoglycemia following PA.