High-intensity interval training: safe and beneficial physical activity strategy in adolescents with type 1 diabetes.

Introduction: Cardiovascular risk factors and depressive symptoms are common in adolescents and young adults with type 1 diabetes (T1D). While exercise improves cardiovascular health and metabolic control, its mental health benefits remain unclear. High intensity interval training (HIIT) has shown an improvement in aerobic capacity without a detrimental decline in blood glucose and home‐based HIIT has reduced barriers towards exercise in adults with T1D. There is scant evidence in children with T1D. Aims: Evaluate metabolic effects of HIIT (time in range, glycemic variability, HbA1c, lipid profile, blood pressure, and body composition). Secondary outcomes included assessing aerobic capacity, strength endurance, depressive symptoms, and barriers towards physical activity. Methods: Prospective, longitudinal, multicenter study involving adolescents (aged 12 and 19) with T1D diagnosed for ≥1 year, at least Tanner stage III, HbA1c between 7-11.5%, and a total daily insulin dose ≥0.7 units/kg/day. Outcomes were assessed at baseline, 1, 3, and 3 months after intervention. Results: 22 participants completed intervention (mean age: 14.32±1.62 years) showing no changes in HbA1c or time in range. Mean blood glucose significantly declined during sessions (191.61±13.69 to 159.95±13.04 mg/dL, p<0.001), with no increase in time in hypoglycemia. Body lean mass increase and fat mass decline after 3 months of training (40.84 ± 8.53 to 42.35 ± 8.34, p<0.001 and 29.94 ± 8.99 to 28.85 ± 9.20, p=0.010, respectively). Maximal oxygen consumption improved once the intervention was completed (33.86±4.00 to 36.43±3.64, <0.001). Lack of motivation and concerns regarding weather decreased after training (73% vs. 59% and 27% vs 14%, respectively). Conclusions: HIIT improved physical fitness and body composition maintaining glycemic stability, being a safe regimen to encourage physical activity in adolescents with TD1.