The aim of this study was to investigate the impact of glycemic control on clinical periodontal status, levels of malondialdehyde (MDA), glutathione peroxidase (GSH-Px), reduced glutathione (GSH) and paraoxonase (PON) activity in gingival crevicular fluid (GCF) and blood samples of type 2 diabetes mellitus (T2DM) patients with chronic periodontitis (CP).