Association between interleukin-6 -174G>C and -634C>G polymorphism and diabetic nephropathy: a meta-analysis

Introduction: We aimed to meta-analyze the association of interleukin (IL)-6 -174G>C and -634C>G polymorphisms with Diabetic Nephropathy (DN). Methods: Relevant studies were searched up to September 2015. Heterogeneity among the eligible studies was assessed by chi-square’s Q-statistic and I2 statistics. The random effect model was used for meta-analysis when significant heterogeneity was found. Otherwise, the fixed effect model was performed. Pooled odds ratios (ORs) and corresponding 95% confidence intervals (95% CIs) were calculated for evaluating the association of IL-6 -174G>C and -634C>G polymorphisms with DN susceptibility. Moreover, subgroup analyses were performed according to the excretion rate of urinary albumin. The funnel plot was used to evaluate the publication bias. Results: A total of 7 studies were included in this study. The overall ORs showed that IL-6 -634C>G polymorphism significantly associated with the risk of DN (dominant model GG+GC vs. CC, pooled OR = 1.52, 95% CI: 1.21-1.91, P = 0.0003; recessive model GG vs. GC+CC, pooled OR = 2.41, 95% CI: 1.36-4.28, P = 0.003 and C-allelic model G vs. C, pooled OR = 1.59, 95% CI: 1.36-4.28, P = 0.003). No significant association was discovered between -174G>C polymorphism and DN. Result of subgroup analysis was identical with the overall models (P > 0.05). No obvious publication bias was found for the included studies. Conclusions: This meta-analysis indicates that IL-6 -634C>G polymorphism is a risk factor for DN, while IL-6 -174G>C polymorphism is not associated with DN.