Introduction: Cardiovascular autonomic neuropathy (CAN) is a significant risk factor for cardiovascular morbidity, mortality in patients with diabetes mellitus (DM). On the other hand, oxidative stress is one of the important factor of pathogenesis of diabetic complications. However, an association between CAN, cardiovascular autonomic reflex tests (CARTs), heart rate variability (HRV) and markers of oxidative stress in patients with DM was not fully investigated.

Objectives: The aim of this study was to investigate the relationship of CAN, CARTs, HRV and oxidative stress markers in patients with type 2 DM.

Materials and methods: We examined 15 patients with type 2 DM, six males and nine females (aged 60,1 ± 1,61 years, duration of diabetes – 10,3 ±1,26 years, HbA1c – 9,1 ± 0,69%) (data are presented everywhere as mean ± s.e.m.). All patients were performed CARTs by Ewingand the followingmarkers of oxidative stress were measured in the plasma – superoxide dismutase, catalase, glutathione peroxidase, malondialdehyde. The diagnosis of CAN was confirmed in patients with 2 positive tests. The statistical analysis was performed using SPSS statistical package version 23.0 for Windows.

Results: CAN by 2 abnormal tests was diagnosed in 33,3% patients, and by 3 abnormal tests – in 66,7% patients. We found positive correlation between levels of glutathione peroxidase and the 30:15 ratio, (r = 86.3, P < 0.05), and level ofcatalase and LF:HF ratio (r = 2.56, P < 0.01). Negative correlation was found between level of catalase and Valsalva ratio, (r = −5.4, P < 0.05).

Conclusion: We found somerelationship between the presence of CANand markers of oxidative stress which could suggest the possible role of oxidative stress in the development of CAN in patients with type 2 DM.