Background and aims: Maintaining glucose levels in the target range during aerobic training and athletic competition is especially difficult. The use of Automated Insulin Delivery (AID) technology is increasing, but exercise continues to be a challenge for persons with type 1 diabetes (T1D). In this case report series, we present 3 cases (C1, C2 and C3) of persons with T1D who used the MiniMed 780G during marathon races. We describe the strategies they used before, during and after the race to manage their glycaemia as well as the results of these strategies on their glycaemic control during the race. Methods: The Medtronic CareLink platform was employed to remotely access insulin pump settings and glycaemic outcomes. Race parameters were obtained from sport watches. Supplemental data were obtained through interviews. Results: Carelink data for Cases 1, 2, and 3 before the race were downloaded: Time in range (TIR) 70-180 mg/dL 89%, 76%, 82%; time above range (TAR) > 180 mg/dL, 9%, 20%, 16%; time below range (TBR) < 70 mg/dL, 1%, 4%, 1%, respectively. The breakfast insulin reduction percentages were -25%, 0%, and 0% for C1, C2, and C3, respectively. In all three cases, insulin dose reduction was applied to the pre-race snack at percentages of -50%, -100% and -83%. The consumption of carbohydrates during the race was 0.39 g/kg/hour, 0.42 g/kg/hour, and 0.5 g/kg/hour, respectively. The total amount of carbohydrates consumed was 101 g, 120 g, and 115 g, respectively. Throughout the race, a temporary target was used for all cases. Conclusions: These cases provide insights for healthcare professionals who assist athletes with T1D using AID systems during prolonged physical activities. Highlighting the significance of specialised education, planning, and personalised approaches.