Effects of moderate to vigorous-intensity physical activity on nocturnal and next day hypoglycemia in adolescents with Type 1 Diabetes

Physical activity (PA) provides many benefits to adolescents with Type 1 Diabetes (T1D); however, adolescents with T1D tend to have lower fitness and PA levels. One reason adolescents with T1D engage in less PA is due to a fear of hypoglycemia. Most studies examining PA in relation to glycemic control measure PA through self-report, thus introducing bias. The purpose of this study was to objectively monitor PA and glucose in adolescents with T1D to examine the temporal associations between moderate and vigorous intensity physical activity (MVPA) and hypoglycemia.

Twenty participants (14 to 19 yr, n=10 females and 10 males) with a T1D diagnosis for at least 1 year were recruited. Participant fitness was evaluated via indirect calorimetry during a maximal treadmill exercise test, and body composition was measured using air displacement plethysmography. An accelerometer (GENEActiv, Activinsights Ltd, Kimbolton, UK) was worn on the wrist continuously for 7 days and the waveform data used to estimate MVPA in min/d. Blood glucose values were simultaneously tracked using continuous glucose monitoring (DexCom SEVEN PLUS, San Diego, CA). After controlling for gender, % body fat (%BF), and fitness, the likelihood of hypoglycemia (¡Ü 70 mg/dl) at nighttime or the next day due to MVPA was examined using logistic regression.

Participants were of avg fitness (females: 43.9 ml/kg/min; males: 49.8 ml/kg/min) and fatness (females: 26.2%; males: 19.2%), and 63.2% of participants met the US federal guidelines of accumulating 60 min/d of MVPA. Hypoglycemia was 22% more likely in those who had 30 min/d more MVPA than those with less (95% CI: 1.03, 1.45; p =0.022).

The results indicate that participating in MVPA increases the risk of hypoglycemia during the night time and the following day. The relationship is independent of gender, %BF and fitness. While promoting PA as a healthy behavior, it is important to educate adolescents with T1D on prevention of hypoglycemia following PA.