Interleukin-6-174G/C polymorphism is associated with a decreased risk of type 2 diabetes in patients with chronic hepatitis C virus

BACKGROUND Chronic hepatitis C(CHC)is associated with type 2 diabetes mellitus.Although the pathogenesis remains to be elucidated,a growing evidence has suggested a role of pro-inflammatory immune response.Increased serum concentrations of Interleukin 6(IL-6)have been associated with insulin resistance,type 2 diabetes mellitus as well as advanced forms of liver disease in chronic hepatitis C infection.AIM To investigate the frequency of IL-6-174G/C(rs1800795)single nucleotide polymorphism(SNP)in CHC patients and in healthy subjects of the same ethnicity.Associations between type 2 diabetes mellitus(dependent variable)and demographic,clinical,nutritional,virological and,IL-6 genotyping data were also investigated in CHC patients.METHODS Two hundred and forty-five patients with CHC and 179 healthy control subjects(blood donors)were prospectively included.Type 2 diabetes mellitus was diagnosed according to the criteria of the American Diabetes Association.Clinical,biochemical,histological and radiological methods were used for the diagnosis of the liver disease.IL-6 polymorphism was evaluated by Taqman SNP genotyping assay.The data were analysed by logistic regression models.RESULTS Type 2 diabetes mellitus,blood hypertension and liver cirrhosis were observed in 20.8%(51/245),40.0%(98/245)and 38.4%(94/245)of the patients,respectively.The frequency of the studied IL-6 SNP did not differ between the CHC patients and controls(P=0.81)and all alleles were in Hardy-Weinberg equilibrium(P=0.38).In the multivariate analysis,type 2 diabetes mellitus was inversely associated with GC and CC genotypes of IL-6-174(OR=0.42;95%CI=0.22-0.78;P=0.006)and positively associated with blood hypertension(OR=5.56;95%CI=2.79-11.09;P<0.001).CONCLUSION This study was the first to show that GC and CC genotypes of IL-6-174 SNP are associated with a decreased risk of type 2 diabetes mellitus in patients chronically infected with hepatitis C virus.The identification of potential inflammatory mediators involved in the crosstalk between hepatitis C virus and the axis pancreas-liver remains important issues that deserve further investigations.