PROJECT SUMMARY Cardiovascular disease (CVD) is the leading cause of death for people with type 1 diabetes (T1D), and abnormalities preceding overt CVD (left ventricular hypertrophy, diastolic dysfunction) are more prevalent in T1D as early as childhood. Disparities in CVD and its risk factors within T1D according to the social construct of race/ethnicity are concerning, especially given rising incidence of T1D specifically in non-Hispanic Black (NHB) and Hispanic youth. Such youth are more likely to have elevated weight, blood pressure, lipids, and glycemia than non-Hispanic White (NHW) youth from T1D diagnosis onward, and NHB individuals experience twice the CVD mortality and 8 times the CVD event rate as NHW peers. Prior studies of CVD within T1D focused on NHW participants with ≥25 years T1D duration treated in an earlier clinical environment, and therefore do not reflect today’s increasingly diverse T1D population with ostensible access to modern diabetes technologies and subspecialty care networks. We and others have reported that social determinants of health (SDOH), including socio-economic factors (low income, limited parental education, food insecurity), inadequate health behaviors (unhealthy diet, physical activity and sleep patterns, smoking), and healthcare access barriers (lack of, or limited, health insurance, high out-of-pocket costs), are associated with lower quality of T1D care and worse T1D outcomes. The impact of SDOH on CVD risk factors and subclinical abnormalities within diverse T1D populations is not known, yet critical for informing multi-level CVD prevention strategies for T1D. We propose to investigate whether SDOH-related barriers may account for racial/ethnic disparities in CVD risk factor trajectories from diagnosis onward and subclinical abnormalities in early adulthood. We will enroll 1000 participants from the SEARCH for Diabetes in Youth Study, including 300 Hispanic or NHB young adults. We will rigorously investigate racial/ethnic differences in prevalence of subclinical CVD in early adulthood (mean age 25 years, T1D duration 16 years) via new assessments of structural and functional abnormalities of the heart and vascular system (with echocardiography, carotid ultrasonography, vascular tonometry). Longitudinal modeling of CVD risk factor trajectories (weight, lipids, blood pressure, A1c, albuminuria, autonomic function), SDOH factors (as defined by Health People 2030) collected from diagnosis onward will enable us to understand how and which SDOH barriers account for racial/ethnic differences in CVD outcomes within T1D. Our aims are 1) To quantify racial/ethnic disparities in trajectories of CVD risk factors, and in subclinical cardiac and vascular outcomes during early adulthood among SEARCH participants with youth-onset T1D.; 2) To understand which SDOH-related barriers are associated with CVD risk factor trajectories and subclinical cardiac and vascular outcomes, using mixed methods; and 3) To determine if ...