Purpose: To assess glycemic control and safety of children and adolescents with type 1 diabetes participating in a 2-day football tournament. Methods: In total, 189 children with type 1 diabetes from 11 diabetes care centers, in Poland, participated in a football tournament in 3 age categories: 7–9 (21.2%), 10–13 (42.9%), and 14–17 (36%) years. Participants were qualified and organized in 23 football teams, played 4 to 6 matches of 30 minutes, and were supervised by a medical team. Data on insulin dose and glycemia were downloaded from personal pumps, glucose meters, continuous glucose monitoring, and flash glucose monitoring systems. Results: The median level of blood glucose before the matches was 6.78 (4.89–9.39) mmol/L, and after the matches, it was 7.39 (5.5–9.87) mmol/L (P = .001). There were no episodes of severe hypoglycemia or ketoacidosis. The number of episodes of low glucose value (blood glucose ≤3.9 mmol/L) was higher during the tournament versus 30 days before: 1.2 (0–1.5) versus 0.7 (0.3–1.1) event/person/day, P < .001. Lactate levels increased during the matches (2.2 [1.6–4.0] mmol/L to 4.4 [2.6–8.5] mmol/L after the matches, P < .001). Conclusions: Large football tournaments can be organized safely for children with type 1 diabetes. For the majority of children, moderate mixed aerobic–anaerobic effort did not adversely affect glycemic results and metabolic safety.