Key Takeaway: In a 16-week trial funded by the NIDDK and Tandem Diabetes Care, 101 children ages 6-13 with type 1 diabetes were randomized to a closed-loop system of insulin delivery (n=78) or the control group (n=23) where patients used a sensor-augmented insulin pump. Children using the closed-loop system, consisting of a t:slim X2 insulin pump with Control-IQ technology and a Dexcom G6 CGM, saw a significant time in range (TIR) improvement (target 70-180 mg/dL) from 53% at baseline to 67% (equivalent to 3.4 more hours per day; p<0.001) at the end of the study. The control group saw a smaller TIR increase from 51% at baseline to 55% at the end of the study. Notably, TIR increased most significantly overnight with children reaching 80% overnight TIR compared to 54% in the control group. The treatment effect was evident in the first month and appeared consistent over 4 months. Control-IQ technology demonstrated benefits across a broad range of baseline characteristics and proved easy to use for children and their parents.