The ratio of insulin-like growth factor-I/insulin-like growth factor–binding protein-3 in sera of patients with hepatitis C virus–related chronic liver disease as a predictive marker of insulin resistance

Recent studies have elucidated a lower level of serum insulin-like growth factor-I (IGF-I) or a decrease in the IGF-I/IGF-binding protein-3 (IGFBP-3) ratio in patients with type 2 diabetes mellitus or hepatic steatosis. Persistent hepatitis C virus (HCV) infection often evokes metabolic abnormalities including hepatic steatosis and insulin resistance. We hypothesized that the relationship between the ratio of IGF-I/IGFBP-3 and the severity of hepatic steatosis or insulin resistance would be observed in patients with HCV-related chronic liver disease (CLD). On the basis of the classifications proposed by Brunt and colleagues (Am J Gastroenterol 1999; 94: 2467-2474), among the 42 enrolled patients with HCV-related CLD, 23 of them had no hepatic steatosis (grade 0), 14 had grade 1 steatosis, and 5 had grade 2 steatosis. The levels of serum IGF-I in the enrolled patients declined in proportion to the severity of hepatic steatosis, whereas serum IGFBP-3 levels did not affect its severity. Therefore, the ratio of IGF-I/IGFBP-3, which corresponds to the circulating free IGF-I status, was significantly lower in those patients with hepatic steatosis (grades 1 and 2) than in those without hepatic steatosis. Serum IGF-I levels significantly correlated with serum zinc levels (r = 0.370, P = .0266), but IGFBP-3 levels did not. However, the linear regression analysis revealed an inverse correlation between the IGF/IGFBP-3 ratio and the value of homeostasis model for assessment of insulin resistance (r =−0.411, P = .0094). These findings suggest that the decline of the circulating free IGF-I level, which derives from zinc deficiency, may contribute to hepatic steatosis and insulin resistance in patients with HCV-related CLD.