Association of Overt Diabetes Mellitus with the Non-CC but not the CC Genotype of Interleukin-28B in Hepatitis C Virus Infected Patients

Background: Interleukin-28B (IL-28B) polymorphism is an important predictor for hepatitis C virus (HCV) treatment response. Whether IL-28b genotypes also influence other nontreatment related clinical parameters is unclear. Methods: Patients with HCV-related chronic liver diseases who attended our department during 2012-2014 were retrospectively analyzed. The single nucleotide polymorphisms (SNPs) of rs12979860 (IL-28B) were correlated with various clinical parameters. We also compared these parameters in patients with and without overt diabetes to identify possible associations. Results: A total of 115 patients were included (median age 48, range 15-76 years; 70% males). Overall, 43/115 (37%) patients had chronic hepatitis, while the remaining 72/115 (63%) had cirrhosis. The most common IL-28B genotype was CC, which was found in 53% of patients (61/115), while the remaining 47% were nonCC [CT 42% (48/115) and TT 5% (6/115)]. Clinical and laboratory parameters like Hb, white blood cell (WBC), platelets, bilirubin, transaminases, and albumin were similar in the CC and nonCC genotypes. Overt diabetes mellitus was present in 22% (25/115) of patients. Patients with nonCC genotype had significantly higher prevalence of overt diabetes mellitus than patients with CC genotype (31% [17/54] versus 13% [8/61]; p < 0.05). When parameters were compared in patients with and without overt diabetes mellitus, only IL-28B and age were significantly associated with overt diabetes mellitus (p < 0.05). Conclusion: In HCV patients, overt diabetes mellitus was more commonly associated with the nonCC genotype of IL-28B than the CC genotype. Carriers of the T-allele of SNP rs12979860 were more likely to have insulin resistance than CC homozygotes, and this finding may explain the higher prevalence of diabetes in non-CC genotypes. Thus, an IL-28B test may be useful in patients of HCV in order to determine their likelihood of developing diabetes mellitus.