 Subjects with intensively-treated type 1 diabetes and glycated hemoglobin HbA1c 7.0-10.0 in 3 age groups 25, 15-24, 8-14 will be randomized to a continuous glucose monitoring CGM group or control group. The primary outcome is change in HbA1c after 26 weeks. A parallel randomized trial is being conducted for a second cohort with HbA1c 7.0 that will follow an identical protocol to that of the first cohort with HbA1c 7.0. 