Hepatitis C Virus-Induced Insulin Resistance: Not All Genotypes Are the Same  Brent A. Neuschwander–Tetri  Gastroenterology  Volume 134, Issue 2, Pages 619-622 (February 2008) DOI: 10.1053/j.gastro.2007.12.041 Copyright © 2008 AGA Institute Terms and Conditions

Figure 1 Insulin resistance (IR) has 4 major causes: genetic predisposition, aging, obesity (especially centripetal obesity), and a sedentary lifestyle. There are also genetic factors that predispose to obesity and possibly impaired muscle function, which could promote a sedentary lifestyle. The paper by Moucari et al6 and earlier data place HCV, especially genotypes 1 and 4, on the left-hand causative side of the diagram. Although there are mechanistic explanations why HCV-induced insulin resistance occurs at the cellular level, it is possible that the effect of HCV infection might be more indirect by promoting fatigue and a sedentary lifestyle in some patients. The consequences of insulin resistance are many and include NAFLD. Altered humoral responses to HCV infection caused by insulin resistance or the associated hyperinsulinemia may also impair the ability to clear the virus. Note that commonly used criteria for the metabolic syndrome include both a causative factor (centripetal obesity) and consequences of insulin resistance (hypertension, dyslipidemia, impaired fasting glucose) and thus the metabolic syndrome as it is currently conceived cannot be viewed as a consequence of insulin resistance. Gastroenterology 2008 134, 619-622DOI: (10.1053/j.gastro.2007.12.041) Copyright © 2008 AGA Institute Terms and Conditions