Tumour necrosis factor-α −308G/A polymorphism is associated with insulin secretory defects in Bangladeshi prediabetic/diabetic subjects

OBJECTIVES: Tumour necrosis factor (TNF)-α, an adipocytokine, is closely linked to impaired glucose tolerance (IGT) and insulin resistance (IR) in type 2 diabetes (T2D) subjects. The relationship between the polymorphisms in the TNF-α gene and IR in Bangladeshi prediabetes and T2D subjects has not yet been fully identified. This study aims to reveal the association between TNF-α gene polymorphism and IR in hyperglycaemic patients of Bangladeshi origin. METHODS: In our study, 106 IGT, 100 T2D, and 109 healthy subjects of Bangladeshi origin were recruited to identify the impact of TNF-α gene polymorphism at position −308 with a G>A transition using PCR and subsequent restriction fragment length polymorphism (RFLP). RESULTS: The −308G>A TNF-α genotype frequency distribution within the control, IGT, and T2D groups showed a significant association (χ(2) = 21.077; P = 0.001), although allele frequency distribution within the groups showed a statistically non-significant difference (χ(2) = 1.696; P = 0.091). β-cell functional deficiency (HOMA-B%) was observed to be significantly (P = 0.034) lower in subjects with a variant genotype. In addition, our results indicate that the study subjects’ body mass index (BMI) and residence status were positively correlated (P ≤ 0.05) with −308G>A TNF-α gene polymorphism. CONCLUSIONS: Therefore, it can be concluded that −308G>A TNF-α gene polymorphism may have a causative relationship with lower insulin secretory capacity and higher BMI in Bangladeshi IGT and T2D populations, while the urban population's lifestyle might be associated with this polymorphism.