Inflammation has received considerable attention in the pathogenesis of type 2 diabetes mellitus (T2DM). Supporting this concept, enhanced expression of interleukin (IL)-1β and increased infiltration of macrophages are observed in pancreatic islets of patients with T2DM. Although IL-1 receptor antagonist (IL-1Ra) plays a major role in controlling of IL-1β-mediated inflammation, its counteraction effects and epigenetic alterations in T2DM are less studied. Thus, we aimed to analyze the DNA methylation status in IL1RN, RELA (p65) and NFKB1 (p50) genes in peripheral blood mononuclear cells (PBMCs) from treated T2DM patients (n = 35) and age-/sex- matched healthy controls (n = 31). Production of IL-1β and IL-1Ra was analyzed in plasma and supernatants from LPS-induced PBMCs. Immunomodulatory effects of IL-1β and IL-1Ra were studied on THP-1 cells. Average DNA methylation level of IL1RN and NFKB1 gene promoters was significantly decreased in T2DM patients in comparison with healthy controls (P< 0.05), which was associated with the increased IL-1Ra (P< 0.001) and IL-1β (P = 0.039) plasma levels in T2DM patients. Negative association between average methylation of IL1RN gene and IL-1Ra plasma levels were observed in female T2DM patients. Methylation of NFKB1 gene was negatively correlated with IL-1Ra levels in the patients and positively with IL-1β levels in female patients. LPS-stimulated PBMCs from female patients failed to raise IL-1β production, while the cells from healthy females increased IL-1β production in comparison with unstimulated cells (P< 0.001). Taken together, the findings suggest that hypomethylation of IL1RN and NFKB1 gene promoters may promote the increased IL-1β/IL-1Ra production and regulate chronic inflammation in T2DM. Further studies are necessary to elucidate the causal direction of these associations and potential role of IL-1Ra in anti-inflammatory processes in treated patients with T2DM.