Interleukin-6 gene promoter -174G/C polymorphism and insulin resistance: A pilot study

Background: The aim of this pilot study was to evaluate the relationship between interleukin-6 promoter -174G/C (IL-6 -174G/C) polymorphism and insulin resistance (IR) in obese patients with coronary heart disease (CHD). Methods: Twenty obese male patients with CHD were selected from a larger database of patients (n=606). IL-6 -174G/C genotype was previously analysed and only homozygotes with the CC genotype (n=10) or GG genotype (n=10) were selected. IR was measured using the homeostasis model assessment for IR (HOMA-IR) method. Results: Differences in age, body mass index, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), triglyceride (TG), hypertension, IL-6, C-reactive protein and HOMA-IR were not significant between the genotypes (p>0.05), but analysis of a homogeneity-of-slopes model showed that genotype had a significant influence on HOMA-IR (p=0.037), and the interaction between genotype and HDL-C had a pronounced tendency to affect HOMA-IR (p=0.058). Using multiple regression analysis, we found that HDL-C had a significant effect on HOMA-IR (p=0.023), and TG had a tendency to affect HOMA-IR (p=0.066) only in the CC genotype. Conclusions: Our data show that IL-6 -174G/C polymorphism may have a significant effect on IR. A comparison between the effects of various cardiovascular risk factors showed that HDL-C may have a significant effect on HOMA-IR in the CC genotype but not in the GG genotype. Further research is needed to test the preliminary results.