Objective: The development of habit (i.e., behavioral automaticity, the extent to which a behavior is performed with decreased thresholds for time, attention [effort], conscious awareness, and goal dependence), for goal-directed health behaviors facilitates health behavior engagement in daily life. However, there is a paucity of research examining automaticity for Type 1 diabetes self-management in adolescence. This study examined if greater perceived automaticity for diabetes self-management was associated with increased daily selfmanagement, decreased daily self-regulation failures in glucose checking, and more optimal daily glycemic levels in adolescents with Type 1 diabetes. Method: Adolescents aged 13-17 and diagnosed with Type 1 diabetes (n = 79) completed the Self-Report Behavioral Automaticity Index, a measure of automaticity of diabetes self-management (i.e., automaticity of glucose checking, carbohydrate counting, and insulin dosing), and a measure of perceived self-management at baseline. One to 3 months later, a subsample of teens (n = 42) also completed a daily diary for a 7-day period including perceptions of daily self-management, daily selfregulation failures in glucose checking, and daily glucose levels. Results: Greater overall automaticity of diabetes self-management was associated with greater baseline and daily self-management, fewer daily self-regulation failures in glucose checking, and lower average daily mean blood glucose levels but not more optimal daily variations in blood glucose levels. Conclusions: Greater automaticity for diabetes self-management may support more optimal daily diabetes self-management in adolescence. Further research is needed to clarify the benefits and mechanisms of automaticity and explore possible interventions.