Considering the critical function of IL-8 in inflammation, and its possible role in the pathogenesis of DM and CP, the aims of this study were to determine (i) IL-8 plasma levels; (ii) IL-8 (−251A/T, rs4073) and its receptor 2 (CXCR2, +1208C/T, rs1126579) polymorphisms; and (iii) the presence of the selected periodontal bacteria in types 1 and 2 DM patients (T1DM and T2DM) and systemically healthy controls (HC) with known periodontal status. The gene discussed is CXCR2; the disease is diabetes mellitus.