BACKGROUND: Executive functioning (EF) predicts better Type 1 diabetes (T1D) management in the high-risk years after high school, but the daily self-regulation processes involved are unclear. PURPOSE: To examine whether EF is associated with daily self-regulation that minimizes ones exposure or buffers adverse reactions to daily diabetes problems, and to determine whether these patterns become stronger during the transition out of high school. METHODS: A measurement burst design with convenience sampling was used. Seniors in high school with T1D (N = 207; 66% female) completed self-report (i.e., Behavioral Rating Inventory of Executive Functioning) and performance measures of EF (i.e., Delis-Kaplan Executive Function System). A 14-day daily diary assessing self-regulation failures, diabetes problems, affect, and indicators of diabetes management was completed at baseline and 1 year later. RESULTS: Correlations and multilevel modeling were conducted. Lower self-reported EF problems were associated with lower average levels of daily self-regulation failures, and these variables were associated with fewer daily diabetes problems. In contrast, better EF performance was unrelated to average daily self-regulation failures, and was unexpectedly associated with more frequent diabetes problems in year 2. Equally across years, on days participants reported lower than their average levels of daily self-regulation failures, they had fewer diabetes problems, regardless of EF. On days with lower than average diabetes problems, participants reported better diabetes management indicators. EF generally did not buffer daily associations in either year. CONCLUSIONS: Regardless of EF, promoting daily self-regulation may prevent diabetes problems and promote T1D management in daily life at this high-risk transitional time.