Impact of Oxidative Stress on Myocardial Performance in Diabetic Patients: A Focus on Subclinical Left Ventricular Dysfunction Running title: Oxidative Stress in Diabetic Cardiac Dysfunction

Introduction: & Objective Oxidative stress is known to affect left ventricular functions negatively. There is a strong bidirectional connection between diabetes mellitus (DM) and oxidative stress. In parallel, left ventricular dysfunction is observed more frequently, even in DM patients without other risk factors. In this context, the objective of this study is to comparatively investigate the potential relationship between oxidative stress and subclinical left ventricular dysfunction (SCLVD) assessed by myocardial performance index (MPI) in patients with and without DM. Materials: & Methods The sample of this observational cross-sectional single-center study consisted of 151 patients who were evaluated biochemically for oxidative stress and SCLVD by tissue Doppler echocardiography. The sample was divided into two groups: DM and non-DM. Patients’ total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI) values were calculated. The correlation, if any, between OSI and MPI was examined in both groups. The effects of oxidative stress and DM on MPI were analyzed. Results: There were 81 (58% male) and 70 (68.6% male) patients in the DM (mean age: 46.17 ± 10.33 years) and non-DM (mean age: 45.72 ± 9.04 years) groups, respectively. There was no significant difference between the groups in gender. Mean TOS and OSI values of the DM group were statistically significantly higher than those of the non-DM group (5.72 ± 0.55 vs. 5.31 ± 0.50, p= <0.001; and 4.92 ± 1.93 vs. 1.79 ± 0.39, p = <0.001; respectively). On the other hand, the mean TAS value of the DM group was significantly higher than that of the non-DM group (1.21 ± 0.40 vs. 3.23 ±0.51, p= <0.001). There was a significant correlation between OSI and MPI mitral in the DM group (R -0.554 p= <0.001) but not in the non-DM group (R - 0.069, p= 0.249). Conclusions: Both oxidative stress and myocardial dysfunction were found to be more common in patients with DM. The study's findings indicated the negative effect of oxidative stress on myocardial functions. Accordingly, increased oxidative stress caused more significant deterioration in MPI in patients with DM compared to patients without DM.