To evaluate the effects of systemic antibiotics in combination with scaling and root planing (SRP) on periodontal parameters, tooth loss and oral health-related quality of life in diabetes patients. Two independent reviewers screened for controlled clinical trials with at least 6-month follow-up in six electronic databases, registers of clinical trials, meeting abstracts and four major dental journals. After duplicates removal, electronic and hand searches yielded 1,878 records; 18 full-text articles were independently read by two reviewers. To evaluate the additional effect of antibiotic usage, pooled weighted mean differences and 95% confidence intervals were calculated using a fixed effects model. Five studies met the inclusion criteria, four of which were included in meta-analyses. The meta-analyses showed a significant effect favouring SRP plus antibiotic for reductions in mean probing depth (PD) (-0.22 mm -0.34, -0.11) and mean percentage of bleeding on probing (BoP) (4% -7, -1). There was no significant effect for clinical attachment level gain and plaque index reduction. No study reported on tooth loss and oral health-related quality of life. Adjunctive systemic antibiotic use in diabetic patients provides a small additional benefit in terms of reductions in mean PD and mean percentage of BoP. CRD42013006389.