Insulin resistance and steatosis in chronic hepatitis C

In chronic hepatitis C, insulin resistance (IR) and type 2 diabetes mellitus (DM) are more prevalent than in healthy controls or in chronic hepatitis B patients. HCV infection promotes IR mainly through increased TNF-a and cytokine suppressor (SOCS-3) production. Both events inhibit insulin receptor and IRS-1 (insulin receptor substrate) tyrosine phosphorylation. Hepatic steatosis is also 2.5 fold more frequent in hepatitis C virus (HCV) infected patients as compared to the general population. Metabolic factors play a crucial role in the etiology of hepatic steatosis genotype non-3 related, which are also the genotypes with a greater association to IR. However, genotype 3, and particularly 3a, has a greater direct steatogenic capacity, and consequently, in those patients, the association with metabolic factors is weaker. Instead, in genotype 3, steatosis associates with viral factors like viral load. Those metabolic factors influence not only the natural history of HCV infection, as well as associate to an accelerated hepatic fibrosis progression, to a worse prognosis when hepatic cirrhosis is present, namely an increased risk of hepatocellular carcinoma, and to a lower sustained viral response rate. On the other hand, in patients who achieve viral eradication, IR and hepatic steatosis may regress, and return if viral infection recurs, which once again indicates an intrinsic steatosis and IR promoter action by HCV.