Background: Physical exercise is beneficial in people with type 1 diabetes (T1D) but it may relate to variability of glycemic response. Scarce evidence is available on the management of physical activity with automatic insulin delivery systems. Aim: To compare in an RCT different therapeutic/nutritional strategies for prolonged aerobic exercise in people with T1D on hybrid closed-loop systems (HCLS). Materials and methods: According to a randomized three-arm crossover design, 15 low/moderately active individuals with T1D on HCLS, 2 females/13 males, aged 51.5±14.0 years, on three different occasions one month apart, underwent a supervised 10 km, 4-hour hiking session. Three strategies were compared: 1) higher glycemic target (Target); 2) consumption of 15 g of complex carbohydrate, as 25 g of whole grain crackers, every 30 minutes (Snack); 3) combination of the two strategies (Target+Snack). CGM glucose concentrations and insulin doses delivered by HCLS during exercise were downloaded from customized web platforms. Results: During the Target session, time-in-range 70-180 mg/dl was significantly higher (97.7±4.7%) than Snack (83.7±12.1%, p=0.002) and Target+Snack (72.3±14.6%, p<0.001) sessions (overall GLM, p<0.001), and time-above-range 180-250 mg/dl was significantly lower (0.9±3.6%) than Snack (13.2±11.2%, p<0.001) and Target+Snack (19.5±10.4%, p<0.001) (overall GLM, p<0.001). Time-below-range 70-54 mg/dl did not significantly differ between the three interventions (p=0.510). Mean glycemia during the 4 hours of exercise was significantly lower during the Target intervention (113±17 mg/dl) than Snack (136±18 mg/dl, p=0.007) and Target+Snack interventions (150±27 mg/dl, p<0.001) (overall GLM, p<0.001). The coefficient of variation during the Target intervention (16.6±5.9%) was lower than Snack (25.5±8.9%, p=0.005) and Target+Snack (28.5±8.4%, p<0.001) interventions (overall GLM, p<0.001). Conclusion: During a prolonged aerobic exercise session, people with T1D on HCLS showed a good glycemic control. Only modifying the glycemic target was a better strategy than only supplementing complex carbohydrates or combining both interventions.