Evaluation of the Correlation between Non-Alcoholic Fatty Liver Disease and Insulin Resistance

Background: Non-alcoholic fatty liver disease (NAFLD) is one of the most prevalent liver diseases, being associated with type II diabetes mellitus, obesity and dyslipidemia. It seems that insulin resistance observed in those with type II diabetes or in obese persons plays an important role in the pathogenesis of NAFLD. The aim of this study was to evaluate the relationship between NAFLD and insulin resistance, disregarding obesity and diabetes. Methods: This case-control study was performed on those patients with NAFLD referring to Sari Imam Khomeini Hospital in 2007 after obtaining informed consent from patients. After repeated sonography and proved fatty liver, 80 patients were enrolled (34 cases and 46 controls) matched for age, gender and body mass index (BMI). NAFLD was documented in the case group, using ultrasonographic indices. Those in the control group were healthy. ALT and AST were normal in both groups. Fasting plasma glucose, fasting insulin, 2-hour oral glucose tolerance test (OGTT) and insulin-resistance were compared between the two groups. Insulin resistance was calculated using HOMA-IR formula. Results: There were 20 men (58.8%) and 14 women (41.2%) in the case group with the mean age of 38.0±9.4 years. Those in the control group were 27 men (58.7%) and 19 women (41.3%) with the mean age of 39.4±10.5 years. There was no significant difference between the two groups concerning their age, gender or BMI. The mean level of FPG was 91.8±8.4 mg/dl in the case and 92.5±10.1 mg/dl in the control group. The mean level of OGTT was 110.9±18.8 mg/dl in the case group and 103.1±25.8 mg/dl in the control group and the difference was not significant. The mean levels of fasting insulin were 16.1±4.2 mg/dl and 10.3±4.8 mg/dl in the case and control groups, respectively (p<0.001). Insulin resistance was 3.6±0.8 μu/l.mmol/l in the case and 2.3±1.2 μu/l.mmol/l in the control group. Conclusion: Since the intervening factors were identical in both groups, we can conclude that the role of insulinresistance in the pathogenesis of NAFLD is not dependent on age, gender and BMI.