Diagnostic Performance of Triglyceride-Glucose Body Mass Index (TyG-BMI), Fibrosis-4 Index (FIB-4), and Their Combined Model for Clinically Significant Liver Fibrosis in Type 2 Diabetes Mellitus

IntroductionPatients with type 2 diabetes mellitus are at increased risk of clinically significant liver fibrosis, while commonly used noninvasive fibrosis scores do not perform equally well in all patients.The triglycerideglucose body mass index (TyG-BMI) captures metabolic changes and excess body weight and may add information not included in the fibrosis-4 index (FIB-4).This study assessed how well the TyG-BMI and FIB-4 identified clinically significant liver fibrosis when used alone and together. MethodsThis cross-sectional diagnostic accuracy study included 280 patients with type 2 diabetes mellitus.The TyG-BMI and FIB-4 were calculated using the patients' clinical and laboratory measurements.Transient elastography served as the reference test, with liver stiffness measurement ≥8 kPa used to identify clinically significant fibrosis.Accuracy was assessed by receiver operating characteristic analysis and by calculating sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy. ResultsClinically significant liver fibrosis was present in 66 of 280 patients (23.6%).The TyG-BMI showed moderate discrimination, with an area under the curve (AUC) of 0.710 (95% CI 0.633-0.783),while the FIB-4 showed an AUC of 0.801 (95% CI 0.736-0.857).At a FIB-4 cutoff of 1.30, sensitivity was 78.8%, specificity was 69.2%, and negative predictive value was 91.4%.The combined TyG-BMI-FIB-4 model achieved an AUC of 0.850 (95% CI 0.796-0.901),with 78.8% sensitivity, 79.0% specificity, 53.6% positive predictive value, 92.3% negative predictive value, and 78.9% accuracy.The internally validated AUC was 0.845. ConclusionsCombining the TyG-BMI with the FIB-4 improved discrimination for transient elastography-defined clinically significant liver fibrosis compared with either index alone.This approach may improve noninvasive fibrosis risk stratification in patients with type 2 diabetes mellitus, but external validation is required before clinical application.