This systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to evaluate the effect of probiotic and symbiotic supplementation on inflammatory markers among patients with diabetes. Clinical trials were searched using Cochrane Library, EMBASE, PubMed, and Web of Science online databases for relevant trials published until April 2018. Two independent investigators evaluated study eligibility, extracted data, and assessed risk of bias of included clinical trials. Cochran's Q test and I-square (I2) statistic were used to detect heterogeneity among the included. Data were pooled by using the random-effect model and standardized mean difference (SMD) was considered as the summary effect size. From 986 originally identified publications 18 clinical trials with a total of 1337 patients were included. Findings showed that probiotic and synbiotic supplementation among patients with diabetes significantly decreased tumor necrosis factor-α (TNF-α) (SMD = −2.99; 95% CI, −4.77, −1.20; P = 0.001; I2: 96.3), and C-reactive protein (CRP) (SMD = −0.87; 95% CI, −1.27, −0.48; P < 0.001; I2: 90.2); while significantly increased nitric oxide (NO) concentrations (SMD = 1.49; 95% CI, 0.81, 2.16; P < 0.001; I2: 92.1). There were no effects of probiotic and synbiotic supplementation on interleukin-6 (IL-6) levels (SMD = −0.65; 95% CI, −1.88, 0.59; P = 0.30; I2: 94.7). In summary, the current meta-analysis demonstrated probiotic and synbiotic supplementation among patients with diabetes significantly decreased CRP and TNF-α, and increased NO levels, but did not affect IL-6 levels.