Serum Levels of Oxidative Stress Markers in Patients with Type 2 Diabetes Mellitus and Non-alcoholic Steatohepatitis

Introduction. Oxidative stress is one of the key mechanisms responsible for disease progression in non-alcoholic fatty liver disease. The aim of this study was to evaluate the serum levels of oxidative stress markers in patients with type 2 diabetes mellitus (DMT2) and non-alcoholic steatohepatitis (NASH) and test their relationships with clinical and biochemical patient characteristics, compared to patients with DMT2 without non-alcoholic fatty liver disease (NAFLD), and controls.

Materials and methods. In all, 60 consecutive patients with DMT2 and NASH, 55 with DMT2 without NAFLD, and 50 age-and-gender-matched healthy subjects participated in the study. The serum levels of protein carbonyls and 8-isoprostane were determined by ELISA methods, while the serum levels of malondialdehyde (MDA) were detected by means of the spectrophotometric method. Clinical, demographic, and laboratory parameters were examined for all the subjects included in the study. Multivariate logistic regression was used to test the independent predictive factors in the relationships investigated here.

Results. Patients with DMT2 and NASH displayed significantly higher serum levels of protein carbonyls (1.112 ± 0.42 nmol/dL), MDA (6.181 ± 1.81 ng/mL), and 8-isoprostane (338.6 ± 98.5 pg/mL) compared to patients with DMT2 without NAFLD, and controls. Results of multivariate logistic regression analyses indicate that in patients with DMT2 and NASH, the serum levels of oxidative stress markers were independently and positively associated with: HbA1c, duration of diabetes, the UKPDS cardiovascular risk score (for protein carbonyls); age, LDL-cholesterol (for 8-isoprostane); and triglycerides serum levels (for MDA).

Conclusions. Our findings indicate that the process of oxidative stress tends to increase in patients with DMT2 and NASH, compared to patients with DMT2 without NAFLD, and controls. This evidence suggests that an antioxidant therapy might prove useful in the treatment of patients with DMT2 and NASH.