•Covid-19 restrictions disrupted physical activities in children with type 1 diabetes.•Diabetes management worsened in glycemia values and insulin delivery.•Active breaks rather than structured training may interrupt sedentary in children with type 1 diabetes. We explored the physical activity (PA) level and the variation in glycaemic control in children with type 1 diabetes (T1D) before and during the lockdown. Then, we proposed an online training program supported by sport-science specialists. Parents of children with T1D (<18 years) filled out an online survey. Anthropometric characteristics, PA, play, sport and sedentary time and the medical related outcomes were recorded. An adapted online program “Covidentary” was proposed through full-training (FT) and active breaks (AB) modality. 280 youth (11.8 ± 3.3 years) were included in the analysis. We reported a decline in sport (-2.1 ± 2.1 h/week) and outdoor-plays (-73.9 ± 93.6 min/day). Moreover, we found an increase in sedentary time (+144.7 ± 147.8 min/day), in mean glycaemic values (+25.4 ± 33.4 mg/dL) and insulin delivery (71.8% of patients). 37% of invited patients attended the training program, 46% took part in AB and 54% in FT. The AB was carried out for 90% of the total duration, while the FT for 31%. Both types of training were perceived as moderate intensity effort. A decline of participation in sport activities and a subsequent increase of sedentary time influence the management of T1D of children, increasing the risk of acute/long-term complications. Online exercise program may contrast thepandemic's sedentarylifestyle.