Abstract INTRODUCTION One of the pathogenic links between type 2 diabetes mellitus (T2DM) and coronary heart disease (CHD) is low-intensity chronic inflammation, which is limited by FoxP3+ regulatory T cells. MATERIALS AND METHODS A comparative, observational, single-center, single-stage study was carried out. The severity of atherosclerosis was assessed by calculating the Gensini score based on selective coronary angiography. The absolute and relative content of CD4+CD25 high FoxP3+ and CD4+CD25 low FoxP3+ T cells in the blood was evaluated by flow cytometry. RESULTS 57 patients with chronic ischemic heart disease were examined. Patients with a combination of CHF and T2DM are characterized by an increase in the relative and absolute content of FoxP3+CD25 lymphocytes in the peripheral blood and an increase in the intranuclear content of FoxP3 in them, which is more pronounced in patients with disease moderate. atherosclerosis (Gensini score 17 to 45 points). CONCLUSIONS This was the first Latin American study that managed to show the relationship between an increase in the content of low FoxP3+CD25 lymphocytes in the peripheral blood with atherosclerosis in patients with a combination of coronary artery disease and DM2.