Ascher, John P. Roberts “
“Studies using

surrogate NVP-BGJ398 purchase estimates show high prevalence of insulin resistance in hepatitis C infection. This study prospectively evaluated the correlation between surrogate and directly measured estimates of insulin resistance and the impact of obesity and ethnicity on this relationship. Eighty-six nondiabetic, noncirrhotic patients with hepatitis C virus (age = 48 ± 7 years, 74% male, 44% white, 22% African American, 26% Latino, 70% genotype 1) were categorized into normal-weight (body mass index [BMI] < 25, n = 30), overweight (BMI = 25-29.9, n = 38), and obese (BMI ≥ 30, n = 18). Insulin-mediated glucose uptake was measured by steady-state plasma glucose (SSPG) concentration during a 240-minute insulin suppression test. Surrogate estimates included: fasting glucose and insulin, glucose/insulin, homeostasis model assessment (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), insulin (I-AUC) and glucose (G-AUC) area under the curve during oral glucose tolerance test, and the Belfiore and Stumvoll indexes. All surrogate estimates correlated with SSPG, but the magnitude of correlation varied (r = 0.30-0.64). The correlation check details coefficients were highest in the obese. I-AUC had the highest correlation

among all ethnic and weight groups (r = 0.57-0.77). HOMA-IR accounted for only 15% of variability in SSPG in the normal weight group. The common HOMA-IR cutoff of ≤3 to define insulin resistance had high misclassification rates especially in the overweight group independent of ethnicity. HOMA-IR > 4 had the lowest misclassification rate (75% sensitivity, 88% specificity). Repeat HOMA-IR measurements had higher within-person variation in the obese (standard deviation = 0.77 higher than normal-weight, 95% confidence interval = 0.25-1.30,

P = 0.005). Conclusion: Because of limitations of surrogate estimates, caution should be used in interpreting data evaluating insulin resistance especially in nonobese, nondiabetic patients with HCV. HEPATOLOGY 2010 Epidemiologic studies support an association between chronic hepatitis C virus (HCV) infection and type 2 diabetes mellitus.1-3 The mechanism by which HCV may induce diabetes is thought to be related to insulin resistance and potential defects in insulin signaling pathways.4, 5 Guanylate cyclase 2C Studies to date have shown a higher prevalence of insulin resistance in HCV infection compared to hepatitis B virus infection and other causes of liver disease.6 Insulin resistance and diabetes in the setting of HCV infection is of great importance due to its association with increased rates of fibrosis and faster progression of liver disease7, 8 as well as potentially lower response to antiviral HCV therapy.9-11 To date, all human studies except for one that evaluated insulin resistance in the setting of HCV have used surrogate estimates of insulin resistance rather than direct measurements of insulin-mediated glucose uptake (IMGU).