Relation of serum insulin-like growth factor-1 (IGF-1) levels with hepatitis C virus infection and insulin resistance

The prospect of the growing worldwide epidemic of hepatitis C virus (HCV) infection and type 2 diabetes mellitus certainly merits attention toward their controversial relationship. Insulin-like growth factor-1 (IGF-1) plays an important role in glucose homeostasis. This study is a cross-sectional study considered as an initial investigation aimed to evaluate the effect of HCV infection on serum IGF-1, as well as to find out whether IGF-1 has a role in development of insulin resistance (IR) in HCV infection. A total of 45 subjects divided into 3 groups were included in the study: chronic HCV-infected patients (15 patients), chronic HCV-infected diabetic patients (15 patients), and diabetic patients without HCV infection (15 patients), along with 15 healthy controls. HCV RNA was quantified using real-time polymerase chain reaction (PCR). Serum IGF-1 levels were measured by enzyme-linked immunosorbent assay (ELISA). Homeostasis model assessment of insulin resistance (HOMA-IR), insulin sensitivity (HOMA-S), and beta-cell function (HOMA-beta) were determined by previously validated mathematic indexes. Fasting blood glucose, insulin levels, and liver parameters including alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined. IGF-1 levels were significantly lower in the 3 patient groups compared with controls (P = 0.001). The HCV group demonstrated high HOMA-IR and HOMA-beta with a positive correlation between HOMA-IR and either HOMA-beta or fasting insulin (P < 0.001). In addition, a negative correlation was found between IGF-1 levels and both AST and ALT, and HOMA-IR was correlated positively with AST activity (P < 0.05). In HCV patients with detectable viremia, IGF-1 levels were correlated negatively with HOMA-beta (P < 0.01) and with HOMA-IR. However, this correlation did not reach statistical significance (P = 0.074). No significant correlation was found between HCV viral load and the studied parameters. In conclusion, low IGF-I levels might have a role in IR among HCV viremic patients. (Translational Research 2011;158:155-162)