Analysis of G(-174)C IL-6 polymorphism and plasma concentrations of inflammatory markers in patients with type 2 diabetes and peripheral arterial disease

<jats:p><jats:bold>Aims:</jats:bold>To determine whether the G(−174)C interleukin 6 (IL-6) polymorphism influences the development of peripheral arterial disease (PAD) in individuals with type 2 diabetes. This was investigated by comparing the distribution of G(−174)C genotypes between patients with type 2 diabetes and PAD (PAD<jats:sup>+</jats:sup>) and those with type 2 diabetes but without PAD (PAD<jats:sup>−</jats:sup>). Plasma concentrations of IL-6, fibrinogen, C reactive protein (CRP), and vascular endothelial growth factor (VEGF) were also compared in PAD<jats:sup>+</jats:sup>and PAD<jats:sup>−</jats:sup>patients.</jats:p><jats:p><jats:bold>Methods:</jats:bold>Blood samples were collected from 146 PAD<jats:sup>+</jats:sup>and 144 PAD<jats:sup>−</jats:sup>patients.<jats:italic>Sfa</jats:italic>NI was used to determine the G(−174)C genotype. Plasma concentrations of IL-6, fibrinogen, CRP, and VEGF were measured by an enzyme linked immunosorbent assay.</jats:p><jats:p><jats:bold>Results:</jats:bold>The GG genotype was more common in PAD<jats:sup>+</jats:sup>patients than in PAD<jats:sup>−</jats:sup>patients. PAD<jats:sup>+</jats:sup>patients also had increased mean plasma concentrations of IL-6, fibrinogen, CRP, and VEGF compared with PAD<jats:sup>−</jats:sup>patients. Mean plasma concentrations of IL-6, fibrinogen, and CRP in both PAD<jats:sup>+</jats:sup>and PAD<jats:sup>−</jats:sup>patients were higher in those with the GG genotype than in those with the GC or CC genotypes. In contrast, mean plasma concentrations of VEGF in PAD<jats:sup>+</jats:sup>and PAD<jats:sup>−</jats:sup>patients were not significantly different between those with different G(−174)C genotypes.</jats:p><jats:p><jats:bold>Conclusions:</jats:bold>These results support a model in which the GG genotype promotes PAD development among individuals with type 2 diabetes by inducing increased release of IL-6. Higher concentrations of IL-6 among those with the GG genotype is associated with increased plasma concentrations of fibrinogen and CRP.</jats:p>