To evaluate the safety and performance of a new multivariable closed-loop glucose controller with automatic carbohydrate recommendation (MCL) during and after unannounced and announced exercise in adults with type 1 diabetes (T1D).A randomized, three-arm, crossover clinical trial was conducted. Participants completed a heavy aerobic exercise session including three 15-min sets on a cycle-ergometer with 5 minutes rest in-between. In a randomly determined order, we compared MCL control with unannounced (CLNA) and announced (CLA) exercise to open-loop therapy (OL). Adults with T1D, insulin pump users and HbA1c between 6.0-8.5% were eligible. We investigated glucose control during and 3 hours after exercise.Ten subjects (40.8±7.0 years-old; an HbA1c of 7.3±0.8%) participated. The use of the MCL in both closed-loop arms decreased the time <70 mg/dl of sensor glucose (0.0%,[0.0-16.8] and 0.0%,[0.0-19.2] vs. 16.2%,[0.0-26.0], (%,[Percentile 10-90]) CLNA and CLA vs. OL respectively, p=0.047,p=0.063) and the number of hypoglycemic events when compared to OL (CLNA 4 and CLA 3 vs. OL 8; p=0.218,p=0.250). The use of MCL system increased the proportion of time within 70-180 mg/dl (87.8%,[51.1-100] and 91.9%,[58.7-100] vs. 81.1%,[65.4-87.0], (%,[Percentile 10-90]) CLNA and CLA vs. OL respectively, p=0.227, p=0.039). This was achieved with the administration of similar doses of insulin and less amount of carbohydrates.MCL with automatic carbohydrate recommendation performed well and was safe during and after both unannounced and announced exercise maintaining glucose mostly within the target range and reducing the risk of hypoglycemia despite of less amount of carbohydrate intake.