Association of TNF-α 308 G/A Polymorphism With Type 2 Diabetes: A Case–Control Study in the Iranian Kurdish Ethnic Group

OBJECTIVES Tumor necrosis factor-α (TNF-α) plays roles in the development of obesity, insulin resistance, and possibility of Type 2 diabetes mellitus (T2DM). The objective of the current study was to evaluate the association of TNF-α promoter-308 G/A polymorphism with T2DM. METHODS In all, 1038 patients with T2DM and 1023 normoglycemic controls were included in this study. All participants were genotyped using the polymerase chain reaction-restriction fragment length polymorphism method. Genotypic and allelic frequencies were then analyzed in each group. Serum lipids, fasting glucose, fasting serum insulin, homeostatic model assessment of insulin resistance, and hemoglogin A1c levels were determined by conventional methods. RESULTS The allelic frequency of the A allele was significantly different between case and control participants (p = 0.006). Genotypes GA and AA were found to be significantly associated with 2.24- and 3.18-fold increased risk for T2DM, respectively. Similarly, the dominant model of -308 G/A polymorphism was found to have a higher risk for T2DM (odds ratio = 2.34, p = 0.001). Individuals with T2DM carrying the GA + AA genotypes of -308 G/A variation had significantly lower fasting plasma insulin than those carrying GG genotype. CONCLUSION Our findings revealed that there is an association between the TNF-α promoter -308 G/A polymorphism and T2DM in this population.