Background :T regulatory cells (Tregs) are a cornerstone regulator for immune responses and inflammatory reactions. Abnormal number or function of Tregs causes deranged immune response an increasing the autoimmune disorders and inflammatory conditions. Type 1 diabetes mellitus is an autoimmune disease associated with many complications, of which, Cardiovascular complications are fundamental and responsible for profound morbidity and mortality. Understanding the immunopathogenesis of these disorders allows early diagnosis and better management by innovating new therapeutic targets. In this study, we aimed to detect the association between CD4+, CD4+CD8+FOX3+ Tregs, T1DM, and associated cardiovascular complications. Methods: The study included 144 individuals divided into three groups, group 1 included 48 patients suffering from T1DM without cardiovascular complications, group II: included 48 type T1DM patients with cardiovascular complications. Group III: included 48 healthy control subjects. For all participants, markers for inflammation, and cardiovascular involvement were assessed. The percentage of CD4+ CD25+ FOXP3+ Regulatory Tcells (Tregs) was measured by flow cytometry using peripheral blood samples. Results:The level of Treg was lowest in group II and highest in group III, the difference was highly significant P<0.00. Treg in group I significantly correlated with age (r= 0.58, P=0.004), CKmb (r= 0.61, P=0.04) and LDL (r= -.61, P=0.4). While in group II, it correlated with triglyceride, (r= 0.65 and a P =- 0.02). In conclusion, Lower levels of Tregs are associated with cardiovascular complications in TIDM patients.