Epidemiologic studies have reported increased incidence, prevalence and acuity of periodontitis in adults with diabetes and some have also suggested that treating periodontal disease may improve glycemic control in diabetic patients.This meta-analysis was conducted to evaluate the effects of different periodontal therapies on metabolic control in patients with type 2 diabetes mellitus (T2DM) and periodontal disease.We searched the Medline, EMBASE and Cochrane Library (Central) databases up to January 2014 for relevant studies pertaining to periodontal treatments and glycemic control in adults with T2DM. The search terms were periodontal treatment/periodontal therapy, diabetes/diabetes mellitus, periodontitis/periodontal and glycemic control. The primary outcome measure taken from the included studies was glycated hemoglobin (HbA1c).We compared differences in patients’ pre- and post-intervention HbA1c results between a treatment group receiving scaling and root planing (SRP) combined with administration of oral doxycycline (n = 71) and controls receiving SRP alone or SRP plus placebo (n = 72). Meta-analysis was performed using Comprehensive Meta Analysis software.Nineteen randomized controlled trials (RCTs) were identified. Four trials involving a total of 143 patients with T2DM and periodontal disease were determined to be eligible for analysis. Data of 1 study were not retained for meta-analysis because HbA1c results were recorded as median with IQR. Meta-analysis of the included 3 studies revealed no significant differences in HbA1c results between the periodontal treatment group (n = 71) and control group (n = 72) (HbA1c SMD = −0.238, 95% CI = −0.616 to 0.140; P = 0.217).Systemic doxycycline added to SRP does not significantly improve metabolic control in patients with T2DM and chronic periodontitis. Current evidence is insufficient to support a significant association between periodontal therapy and metabolic control in this patient population. However, evidence suggests that periodontal therapy itself improves metabolic control and reinforces that T2DM is a risk factor for periodontitis.