Abstract: Objective The purpose of this study was to investigate impact of poorly-controlled blood glucose on oxidative stress and liver fibrosis in patients with type 2 diabetes mellitus (T2DM) and non-alcoholic fatty liver diseases (NAFLD). Methods A total of 180 patients with T2DM and concomitant NAFLD were encountered in our hospital between January 2022 and December 2024, serum malondialdehyde (MDA), glutathione peroxidase (GSH-PX) were detected by ELISA, suproxide dismulate (SOD) levels was detected by automatic biochemical analyzer. serum glycated hemoglobin (HbA1c) level was routinely obtained and fibrosis index based on the 4 factors (FIB-4) was calculated. Patients were grouped as poorly (n=96)- and well (n=84)-controlled individuals based on HbA1c level, and as low-risk (n=64), medium-risk (n=80) and high-risk subgroup of liver fibrosis (n=36) based on FIB-4 levels. Multivariate linear regression was applied to reveal influencing factors for oxidative stress and liver fibrosis. Results Serum TC level in poorly-controlled blood glucose group was (2.5±0.3) mmol/L, much higher than [(2.1±0.3) mmol/L,P＜0.001], and serum TG level was (4.4±0.5) mmol/L, much higher than [(4.1±0.5) mmol/L,P＜0.001] in well-controlled blood glucose group; serum ALT level was (40.5±6.5) U/L, much higher than [(36.8±6.2) U/L,P＜0.001],and serum AST level was (46.4±7.5) U/L,much higher than [(42.2±6.8) U/L,P＜0.001] in well-controlled blood glucose group; serum MDA level was (25.1±5.1) μmol/L,much higher than [(20.6±4.6) μmol/L,P＜0.001],while serum GSH-PX and SOD levels were (54.4±6.0) ng/L and (53.2±7.6) U/mL,both significantly lower than [(60.9±8.3) ng/L and (69.5±10.2) U/mL,respectivley, P＜0.001] in well-controlled blood glucose group; multivariate linear regression analysis showed that serum AST, HbA1c, MDA, GSH-PX and SOD levels were all the independent impacting factors for liver fibrosis in patients with T2DM and NAFLD (P<0.05). Conclusion Poorly-controlled blood glucose in patients with T2DM and NAFLD might trigger body oxidative stress and lead to liver fibrosis progress.

Key words: Non-alcoholic fatty liver diseases, Type 2 diabetes, Glycated hemoglobin, Oxidative stress, Liver fibrosis factors-4