Experimental: Group A: SHIFT2

Adolescents and young adults will engage in routine medical visits and attend 6 sessions (1x/month) focused on transition preparation and diabetes management with a transition coach and will receive bi-weekly messages during these 6-months that encourage self-management behaviors.~Parents will attend 2 sessions (month 1 and 6) with a transition coach and will receive materials, complementing their child's lesson, 1x/month for months 2-5 that focus on transition their role and supporting their child's diabetes management.

Placebo_comparator: Group B: TAU+/Control

Participants will engage in routine medical visits and will receive education materials monthly (1x/month) regarding healthcare transition and diabetes management.