Adolescents and young adults with T1D and poor glycemic control (age 14-< 25 years, T1D duration >12 months, hemoglobin A1c (HbA1c) 7.5-<11.0%, using an insulin pump or MDI)) will be randomly assigned to either continuous glucose monitoring (CGM) or blood glucose monitoring (BGM). Sample size will be 150. The primary outcome assessment will be HbA1c after 6 months. Secondary outcomes will include HbA1c, CGM metrics (control group will wear blinded CGM at 13 and 24 weeks), and quality of life measures. The randomized trial will be followed by a 6-month extension study during which the randomized controlled trial (RCT) control group will initiate CGM and the RCT CGM group will continue CGM.