Background and objective: The effect of non-surgical periodontal treatment on periodontal condition and metabolic control is a controversial issue. Therefore, the present study was designed to compare the effects of non-surgical periodontal therapy with and without systemic doxycycline on glycemic status and clinical periodontal parameters in type II diabetic patients.

Methods and materials: In this double blind randomized controlled clinical trial, fifty diabetic patients were enrolled. The periodontal therapy involved scaling with ultrasonic curettes. The patients received 100 mg Doxycycline twice on the first day and once per day after that for two weeks in case group and placebo in control group. Plaque Index (PI), Clinical Attachment Level (CAL) and Probing Depth (PD) were recorded on baseline and 1, 2 and 3 months after treatment. FBS(Fasting Blood Sugar) and HbA1C were also recorded at baseline and 3 months after the treatment and analyzed by t and Paired t-Test.

Result: Periodontal parameters such as PD (P<0.04),CAL(P<0.05), and HbA1C (P=0.03)were reduced significantly in Doxycycline group, but FBS had not significant differences between two groups (P=0.7)

Conclusion: Although both periodontal treatment regimens are effective in type II diabetics, the use of Doxycycline as an adjunct provided more significant improvement in periodontal and glycemic control