Fibroblast Growth Factor 21: A More Effective Biomarker Than Free Fatty Acids and Other Insulin Sensitivity Measures for Predicting Non-alcoholic Fatty Liver Disease in Saudi Arabian Type 2 Diabetes Patients.

Background Non-alcoholic fatty liver disease (NAFLD) is more prevalent among individuals with type 2 diabetes (T2DM), elevating their risk of cardiovascular diseases (CVDs) and premature mortality. There is a need to modify treatment strategies to prevent or delay these adverse outcomes. Currently, there are no sensitive or specific biomarkers for predicting NAFLD in Saudi T2DM patients. Therefore, we aimed to explore the possibility of using fibroblast growth factor 21 (FGF-21), free fatty acids (FFAs), homeostatic model assessment for insulin resistance (HOMA-IR), and quantitative insulin sensitivity check index (QUICKI) as possible markers. Methodology In this study, a total of 67 T2DM patients were recruited. NAFLD was detected by ultrasonography in 28 patients. Plasma glucose, FFAs, FGF-21, and serum insulin were measured in fasting blood samples. HOMA-IR and QUICKI were calculated. The means of the two groups with and without NAFLD were statistically compared. The receiver operating characteristics (ROC) curve and the area under the curve (AUC) were used to assess the ability to identify NAFLD. Results The mean levels of FGF-21 and HOMA-IR were significantly higher and that of QUICKI was significantly lower in patients with NAFLD than in those without (p < 0.001, p = 0.023, and p = 0.018, respectively). FGF-21 had the highest AUC to identify NAFLD (AUC = 0.981, 95% confidence interval = 0.954-1, P < 0.001). The AUCs for HOMA-IR, QUICKI, and FFA were <0.7. The highest sensitivity, specificity, positive likelihood ratio, and the lowest negative likelihood ratio were found when FGF-21 was used to predict NAFLD. Conclusions FGF-21 may be used as a biomarker to predict NAFLD in people with T2DM due to its high sensitivity and specificity compared to the other markers.