Glucose requirements to maintain euglycemia after moderate-intensity afternoon exercise in adolescents with type 1 diabetes are increased in a biphasic manner

Context: Exercise increases the risk of hypoglycemia in type 1 diabetes. Objective: This study aimed to investigate how the amount of glucose required to prevent an exercise-mediated fall in glucose level changes over time in adolescents with type 1 diabetes. Setting: The study took place at a tertiary pediatric referral center. Design, Participants, and Intervention: Nine adolescents with type 1 diabetes mellitus ( five males, four females, aged 16 +/- 1.8 yr, diabetes duration 8.2 +/- 4.1 yr, hemoglobin Alc 7.8 +/- 0.8%, mean +/- SD) were subjected on two different occasions to a rest or 45 min of exercise at 95% of their lactate threshold. Insulin was administered iv at a rate based on their usual insulin dose, with similar plasma insulin levels for both studies ( 82.1 +/- 19.0, exercise vs. 82.7 +/- 16.4 pmol/liter, rest). Glucose was infused to maintain euglycemia for 18 Main Outcome Measures: Glucose infusion rates required to maintain euglcycemia and levels of counterregulatory hormones were compared between rest and exercise study nights. Results: Glucose infusion rates to maintain stable glucose levels were elevated during and shortly after exercise, compared with the rest study, and again from 7 - 11 h after exercise. Counterregulatory hormone levels were similar between exercise and rest studies except for peaks in the immediate postexercise period ( epinephrine, norepinephrine, GH, and cortisol peaks: 375.6 +/- 146.9 pmol/liter, 5.59 +/- 0.73 nmol/liter, 71.9 +/- 14.8 mIU/liter, and 558 +/- 69 nmol/liter, respectively). Conclusions: The biphasic increase in glucose requirements to maintain euglycemia after exercise suggests a unique pattern of early and delayed risk for nocturnal hypoglycemia after afternoon exercise.