OBJECTIVE： To investigate the effects of minocycline on clinical indexes， inflammatory factors and blood glucose of patients with moderate and severe chronic periodontitis complicated with type 2 diabetes （T2DM）. METHODS： A total of 125 patients with moderate and severe chronic periodontitis complicated with T2DM selected from our hospital during Feb. 2013-Aug. 2015 were divided into control group （63 cases） and observation group （62 cases） according to random number table.  Both groups were periodental non-surgical treatment as scaling and root planning. Control group was given iodine glycerin to fill periodontal pockets after surgery， 2-4 times/d. Observation group was given Minocycline hydrochloride ointment， once a week， after surgery. Both groups were treated for 4 weeks. The levels of clinical indexes [probing depth， clinical attachment level （CAL）， probing bleeding rate]， serum inflammatory factors （CRP， TNF-α） and blood glucose （fasting blood glucose， glycosylated hemoglobin） were observed in 2 groups before treatment， 3 months after treatment， and the occurrence of ADR was recorded. RESULTS： Before treatment， there was no statistical significance in clinical indexes， serum inflammatory factors and blood glucose levels between 2 groups （P＞0.05）. Three months after treatment， probing depth， probing bleeding rate and serum inflammatory factor levels of 2 groups were decreased significantly， and the observation group was significantly lower than the control group， with statistical significance （P＜0.05）. Compared to before treatment， CAL of 2 groups were increased， without statistical significance before and after treatment or between 2 groups （P＞0.05）. The levels of fasting blood glucose in 2 groups were decreased， with statistical significance （P＜0.05）， but  no statistical significance between 2 groups （P＞0.05）. Compared to before treatment， the level of glycosylated hemoglobin in control group was decreased， without statistical significance （P＞0.05）； the level of glycosylated hemoglobin in observation group was decreased significantly， and the observation group was significantly lower than the control group， with statistical significance （P＜0.05）. There was no statistical significance in the incidence of ADR between observation group （3.23％） and control group （0） （P＞0.05）. CONCLUSIONS： For moderate and severe chronic periodontitis complicated with T2DM， minocycline effectively improves clinical indexes of periodontitis， reduces serum inflammatory factors and blood glucose with good safety.