Abstract： Objective To evaluate the effect of non-surgical periodontal therapy on periodontal status, glycemic control and the level of serum interleukin(IL)-6 in type 2 diabetic patients with chronic periodontitis (DMCP). Methods Fifty-five DMCP and 55 systemically healthy patients with chronic periodontitis(CP) were recruited in this study. The diabetes were classified into two groups, the wellcontrolled group [glycated hemoglobin (HbA1c) ＜ 7.00%]and the poorly controlled group (HbA1c ≥7.00%). All subjects received non-surgical periodontal therapy. Periodontal clinical parameters including periodontal probing depth (PD), attachment loss (AL), bleeding index (BI) and plaque index (PLI) were recorded at baseline, 6 weeks and 3 months after the treatment. Fasting plasma glucose(FPG), HbA1c and the concentration of serum IL-6 were measured. Results At 6 weeks and 3 months after treatment, PD,AL, BI, PLI and the concentration of serum IL-6 of both groups significantly reduced(P ＜ 0. 05). The level of IL-6 in diabetic patients reduced significantly from (3.47 ±0.33) ng/L to (3.21 ±0.66) ng/L and to (3.03 ± 0. 54) ng/L. The HbA1c of diabetic patients reduced significantly 3 months after treatment [(6.80±1.21%]compared with the baseline[(7.35 ± 1.73)%, P ＜0.05]. HbA1c of the poorly controlled group reduced significantly(P ＜0. 05), while HbA1c of the well-controlled diabetes did not show any apparent reduction (P ＞ 0. 05). Conclusions Non-surgical periodontal therapy can effectively reduce the concentration of serum IL-6, thereby improving glycemic control in type 2 diabetes patients with chronic periodontitis. However, there was no any significant reduction of HbA1c in the well-controlled diabetes.