Sousa GR, et al. - Researchers investigated whether hyperglycemia-induced cardiac autoimmunity could contribute to long-term cardiovascular disease (CVD) complications in type 1 diabetes mellitus (T1DM). Using longitudinal samples from the DCCT (Diabetes Control and Complications Trial), they measured the prevalence and profiles of cardiac autoantibodies (AAbs) in participants with mean hemoglobin A1c (HbA1c) ≥9.0% (n=83) and ≤7.0% (n=83) during DCCT. Over a 26-year median follow-up, they focused on subsequent coronary artery calcification (measured once during years 7–9 in the post-DCCT EDIC [Epidemiology of Diabetes Interventions and Complications] observational study), high-sensitivity C-reactive protein (measured during EDIC years 4–6), and CVD events (defined as nonfatal myocardial infarction, stroke, death resulting from CVD, heart failure, or coronary artery bypass graft). Matched patients with type 2 diabetes mellitus with HbA1c ≥9.0% (n=70) and ≤7.0% (n=140) and, as a control for cardiac autoimmunity, patients with Chagas cardiomyopathy (n=51) were also assessed for cardiac AAbs. Findings revealed an association between poor glycemic control and cardiac autoimmunity in T1DM. Possibly via inflammatory pathways, a role for autoimmune mechanisms in the development of CVD in T1DM was indicated by the observed association of cardiac AAb positivity with an increased risk of CVD decades later.