In the Journals

Afternoon exercise linked to next-day hypoglycemia in adolescents with diabetes

In adolescents with type 1 diabetes, a 30-minute increase in afternoon/evening moderate-to-vigorous physical activity increased risk for overnight and next-day hypoglycemia, according to study data.

“Higher fitness levels are associated with an increased risk of hypoglycemia,” the researchers wrote. “This indicates the importance of educating adolescents with type 1 diabetes, their parents, and their coaches on prevention of hypoglycemia following activity.”

Moreover, they found that those adolescents who are more physically fit have a greater risk for next-day hypoglycemia after afternoon exercise than their less-fit peers.

The study evaluated 19 participants aged 14 to 20 years, who were diagnosed with type 1 diabetes. The study entailed two visits, spaced 3 to 5 days apart, to the Institute for Clinical and Translational Science at the University of Iowa. At the initial visit, the researchers calibrated and subcutaneously inserted the continuous glucose monitor (CGM) in each patient. They also took anthropometric measurements using air displacement plethysmography and assessed the fitness of the participants using a maximal exercise test. All patients were fitted with an accelerometer on their left wrists at the first visit, and this device tracked moderate-to-vigorous intensity physical activity (MVPA). Logistic regression was used to assess the likelihood of nighttime and next-day hypoglycemia resulting from MVPA.

The participants in the study were found to be of average fitness (females: 43.9 mL/kg/min; males: 49.8 mL/kg/min) and adiposity (females: 26.2% males: 19.2%). Of the adolescents in the study, 63.2% met the US federal guideline of accruing 60 minutes per day of MVPA.

The researchers determined that those who increased MVPA by 30 minutes per day in the previous afternoon were 31% more likely to have hypoglycemia than those with less afternoon MVPA (95% CI, 1.05-1.63). Moreover, those with higher cardiovascular fitness measured by maximal oxygen consumption (VO2 max) had a greater risk for next-day hypoglycemia than those with lower VO2 max.

The researchers said the study focused on afternoon MVPA because these after-school hours are commonly used for recreational activities and school-based sports programs.

Disclosure: One researcher is a consultant for Daiichi Sankyo.