Relationship between the Triglyceride Glucose Index and the Presence and Fibrosis of Nonalcoholic Fatty Liver Disease in Korean Adults

Background: Recently, the triglyceride glucose (TyG) index has been considered a surrogate marker of insulin resistance. Insulin resistance is a well known pathogenic factor in nonalcoholic fatty liver disease (NAFLD). However, few studies have investigated the relationship between the TyG index and liver fibrosis in subjects with NAFLD. Thus, we investigated the relationship between the TyG index and liver fibrosis in Korean adults. Methods: In total, 5158 participants who underwent ultrasonography in a health promotion center were enrolled. Anthropometric profiles and multiple metabolic risk factors were measured. The TyG index was calculated as ln [fasting triglycerides (mg/dL) × fasting glucose (mg/dL)/2], and the insulin resistance index of homeostasis model assessment (HOMA-IR) was estimated. NAFLD was diagnosed by ultrasonography, and degree of liver fibrosis was assessed by NAFLD fibrosis score (NFS). Significant liver fibrosis was defined as NFS ≥ -1.5. Results: All subjects were stratified into four groups based on their TyG indices. Significant differences were observed in metabolic parameters among the groups, and the prevalence of NAFLD and liver fibrosis by NFS significantly increased with increasing TyG index. When classifying the severity of NAFLD into three groups, there was a significant correlation between the severity of NAFLD and the TyG index. In the logistic regression analysis after adjustment for multiple risk factors, the odds ratio for the prevalence of liver fibrosis, when comparing the highest and lowest quartiles of the TyG index was 1.92 (95% CI: 1.46-2.53; P for trend < 0.01); the odds ratio for the prevalence of liver fibrosis, when comparing the highest and lowest quartiles of HOMA-IR was 2.92 (95% CI: 1.12-2.40; P for trend