Incidence rates of type 1 diabetes are increasing faster in Latinx youth than other ethnic groups, yet this population remains understudied. The current study (1) tested differences in division of diabetes-related responsibility (adolescent alone, mother alone, and shared) across Latinx and non-Latinx White families (N = 118 mother-adolescent dyads, 56 = Latinx dyads, Mage=13.24 years), and (2) examined associations between diabetes responsibility and adolescent health (HbA1c, diabetes self-management behaviors, and depressive symptoms). Latina mothers reported more shared and less adolescent responsibility than non-Latinx White mothers, but there were no ethnic differences in adolescent reports of responsibility. Independent of demographic and illness-related characteristics, mother- and adolescent-reports of shared responsibility were associated with higher self-management behaviors, while individual responsibility (adolescent or mother alone) was generally associated with lower self-management behaviors. Shared responsibility associations with higher mother-reported self-management behaviors occurred among Latinx families, but not non-Latinx White families. Shared and individual responsibility were not associated with HbA1c or depressive symptoms. The findings suggest the importance of shared responsibility for diabetes management in adolescence, particularly in Latinx families.