Relationship between the levels of serum high-sensitivity C-reactive protein and interleukin-6 and interleukin-6 gene polymorphisms in type 2 diabetes mellitus

There has been growing evidence that low-grade activation of the immune system plays a role in the pathogenesis of insulin resistance and type 2 diabetes mellitus (T2DM). This study was based on the hypothesis that a single-nucleotide polymorphism in the promoter region of the interleukin-6 (IL-6) gene influences its transcription and thus affects serum levels of IL-6 and hence of the high-sensitivity C-reactive protein (hs-CRP). This may lead to insulin resistance and consequently type 2 diabetes. This study was performed on 60 subjects: 30 T2DM patients and 30 non-diabetic participants. For all subjects, the serum level of IL-6 was assayed by enzyme chemiluminescence, serum hs-CRP was assayed using a particle-enhanced immuno-turbidimetric assay and the IL-6 -174G/C gene polymorphism was detected by PCR-RFLP. There was no statistically significant association between the IL-6 -174G/C gene polymorphism and the presence of diabetes mellitus or with IL-6 or hs-CRP levels. The GG genotype was the most prevalent genotype in the participants studied and the presence of the C allele in the -174 position of the promoter region might be protective. However, the serum levels of IL-6 and hs-CRP were found to be higher in the diabetic than the non-diabetic group, reflecting the role played by both markers in the pathogenesis of T2DM. © 2011 Springer-Verlag London Limited.