Context: Type 2 diabetes mellitus (T2DM) is a multi-factorial disease with several genetic
and environmental factors known to be associated with the disease. Tumor necrosis factoralpha
(TNF-α) acts on fat cells associated with increased insulin resistance and obesity
and its increase can be associated with the prevalence of T2DM. Previous studies on the
relationship between 308 G/A polymorphism in TNF-α and T2DM were not conclusive.
The aim of this study was to investigate the association between 308 G/A polymorphism
in TNF-α gene and T2DM using a systematic review and meta-analysis.
Evidence Acquisitions: In this systematic review we searched all published studies about the
association between TNF 308 G/A polymorphism and T2DM through databases such as
Scopus, Science direct, PubMed and Google scholar. A fixed or random effect model was
used on the basis of heterogeneity. The heterogeneity was assessed using the I2 index. We
used STATA software (version 11.2) for data analysis.
Results: In 22 selected papers, the total number of T2DM and control subject was 8485
and 8615, respectively. Odds ratios (ORs) with 95% confidence intervals(CI) for the GG
genotype polymorphism 308 G/A in total, Asian populations and whites (Caucasian) were
estimated as OR=0.98 (95% CI: 0.96-1.00), OR=0.96 (95% CI: 0.93 to 0.99) and OR=1.00
(95% CI: 0.97 to 1.40). The Publication Bias/or heterogeneity was observed in this study.
Conclusions: The present investigation have shown that 308 G/A polymorphism GG and
GA genotypes in TNF-α gene cannot be considered as predictors of T2DM (P<0.05).