Association of Insulin Resistance with Alanine Aminotransferase Activity in Patients with Nonalcoholic Fatty Liver Disease

AbstractObjectiveElevated liver enzymes have been recognized as a predictor for the development of metabolic syndrome and type 2 diabetes mellitus in patients with nonalcoholic fatty liver disease (NAFLD). However, the association of insulin resistance with alanine aminotransferase (ALT) activity remains largely unknown.Patients and MethodsA total of 454 subjects attending the health examination center were enrolled from September 2005 through December 2006. Of them, 203 patients (male/female, 113/90; mean age, 50.9 years) were identified to have NAFLD. Their insulin resistance index was determined using the homeostasis model assessment (HOMA-IR). Elevated ALT level was defined as > 30 IU/L for male and > 19 IU/L for female subjects according to the new cut-off values.ResultsThere were 113 subjects in the elevated ALT group and 90 in the normal ALT group. Age, gender and the prevalence of diabetes mellitus, hypertension and smoking history were comparable between these two groups. The elevated ALT group had higher readings for body mass index, triglyceride, total cholesterol, low-density lipoprotein cholesterol, insulin and HOMA-IR than the normal ALT group using univariate analyses. Multivariate logistic regression analyses showed that only log(HOMA-IR) was positively associated with elevated ALT level in the NAFLD patients (adjusted odds ratio, 5.04; 95% confidence interval, 1.56–16.27).ConclusionOur data showed that there was an association between insulin resistance and serum ALT levels in NAFLD patients, independent of other metabolic factors. However, further longitudinal studies are needed to clarify the causal relationship between insulin resistance and increased ALT activity in patients with NAFLD