Objective: To study the relationship between liver fat content (LFC) and liver enzymes in individuals with various statuses of glucose metabolism.
Methods: A total of 109 subjects including with impaired glucose regulation (IGR) (n = 31), newly diagnosed type 2 diabetes (NT2DM) (n = 31) and normal glucose tolerance (NGT) (n = 47) were recruited. The level of LFC was measured by (1)H magnetic resonance spectroscopy ((1)H-MRS) to study the relationship between liver fat content (LFC) and alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AKP) and γ-glutamyltransferase (GGT). The receiver operating characteristic curve (ROC) was employed to obtain the optimal cut-off point of ALT to predict the occurrence of nonalcoholic fatty liver disease (NAFLD).
Results: (1) The levels of LFC were progressively raised in NGT, IGR and NT2DM groups respectively [3.83 (2.35 - 7.59)%, 12.82 (8.10 - 21.37)% and 21.99 (11.89 - 34.43)%, P < 0.01]; (2) the subjects were divided into four subgroups by the method of LFC quartile. And quartile subgroups Q1-4 were associated with the increase of LFC. Waist, BMI, systolic blood pressure, triglyceride, total cholesterol, fasting plasma glucose, OGTT 2 h postprandial glucose and HOMA-IR had a rising trend from Q2. But HDL-C showed a declining trend from Q2; (3) ALT and GGT significantly increased from Q3 (P < 0.01) while AST and AKP significantly increased in Q4 (P < 0.01); (4) adjusted by gender, age and body mass index (BMI), LFC was positively correlated with AST (r = 0.329, P < 0.05), ALT (r = 0.454) and GGT (r = 0.378) (All P < 0.01). But it was negatively correlated with AST/ALT (r = -0.364, P < 0.01); (5) the analysis of stepwise regression demonstrated that LFC was a predictor of ALT, AST, GGT and AST/ALT; (6) ALT had a ROC(AUC) of 0.813 (male) and 0.769 (female) (All P < 0.01). The optimal cut-off point of 23.5 U/L (male) and 17.5 U/L (female) might predict the occurrence of NAFLD.
Conclusions: Liver enzymes are correlated with LFC even in normal range. The optimal cut-off point of 23.5 U/L (male) and 17.5 U/L (female) might predict the occurrence of NAFLD. The current used ALT upper limit could underestimate the NAFLD.