Abstract: Objective This study was aimed at exploring the implication of serum leptin, retinol binding protein-4 (RBP4) and cholinesterase (ChE) levels in patients with non-alcoholic fatty liver diseases (NAFLD) and type 2 diabetes mellitus (T2DM). Methods 74 patients with NAFLD and T2DM , including mild fatty liver in 28 cases, moderate in 25 cases and severe in 21 cases, 30 patients with NAFLD, 30 patients with T2DM and 30 healthy individuals were recruited in our hospital between April 2019 and April 2022. Serum leptin and RBP4 levels were detected by ELISA, and serum ChE level was detected routinely. The diagnostic performance was evaluated by the area under the receiver operating characteristic (AUC) curves. Results The HOMA-IR in patients with NAFLD and T2DM was(5.8±1.7), much higher than (3.9±1.1) in patients with T2DM, or (3.6±0.9) in patients with NAFLD or [(1.9±0.4), P＜0.05] in healthy persons, while the insulin sensitivity index was(-4.4±0.5), much lower than(-4.0±0.4) in patients with T2DM or (-4.0±0.3) in patients with NAFLD or healthy persons [(-3.5±0.3), P＜0.05]; serum leptin and RBP4 levels in patients with NAFLD and T2DM were (17.1±3.1)μg/L and (30.6±2.8)mg/L, significantly higher than [(12.3±2.7)μg/L and (24.1±2.3)mg/L, P＜0.05] in patients with T2DM or [(13.1±2.4)μg/L and (23.9±2.7)mg/L, P＜0.05] in patients with NAFLD or [(9.7±1.9)μg/L and (20.1±1.9)mg/L, P＜0.05] in healthy persons, while serum ChE level was (8337.3±755.9)IU/L, much lower than [(9080.2±684.7)IU/L, P＜0.05] in patients with T2DM or [(9159.9±812.2)IU/L, P＜0.05] in patients with NAFLD or [(9987.4±975.4)IU/L, P＜0.05] in healthy persons; serum leptin and RBP4 levels in NAFLD/T2DM patients with severe hepatic steatosis was much higher than, while serum ChE level was much lower than in those with moderate or mild hepatic steatosis(P＜0.05); the AUC was 0.834, with the sensitivity, specificity and accuracy of 76.2%, 81.1% and 79.7% when serum leptin, RBP4 and ChE level combination was applied to predict severe hepatic steatosis in patients with NAFLD and T2DM, much superior to the three parameters alone evaluation ( with AUCs of 0.727, 0.739 and 0.708, respectively, P＜0.05). Conclusion Serum leptin and RBP4 levels increase, while serum ChE level decrease, in patients with NAFLD and T2DM, which might be correlated to hepatic steatosis severity, and help evaluate the disease progression.

Key words: Non-alcoholic fatty liver diseases, Type 2 diabetes mellitus, Insulin resistance, Leptin, Retinol-binding protein 4, Cholinesterase