Association of toll-like receptor 4 polymorphisms with type 2 diabetes mellitus

Toll-like receptor 4 (TLR4) plays important roles in modulating innate immunity. Type 2 diabetes mellitus (T2DM) is a chronic and complex disease that is characterized by impaired insulin resistance and dysregulated immune response. In the current study, we investigated whether TLR4 polymorphisms were correlated with susceptibility to T2DM in the Chinese population. Four TLR4 polymorphisms (-2431T/C, Asp299Gly, Thr399Il3, and +3725G/C) were genotyped in 936 T2DM patients and 978 healthy controls. Results showed that the prevalence of TLR4 +3725GC and CC genotypes was significantly decreased in T2DM cases than those in controls [odds ratio (OR) = 0.68, 95% confidence interval (CI) = 0.55-0.84, p = 0.0003, and OR=0.46, 95% CI = 0.32-0.67, p = 3.71 × 10(-5) , respectively). Also, the frequency of TLR4 +3725C allele was significantly lower in T2DM patients (p = 2.50 × 10(-8) ). The -2431T/C did not reveal any significant differences between cases and controls. We did not detect Asp299Gly and Thr399Il3 polymorphisms in our study group. Stratification analysis of the clinical features in the patients demonstrated that frequency of +3725CC genotype was lower in patients older than 50 years old (p = 0.047). In conclusion, these results indicate that TLR4 +3725G/C polymorphism may be a novel protective factor against T2DM in the Chinese population.