Variation in Arterial Stiffness and Markers of Oxidative Stress in Patients with Type 2 Diabetes Mellitus from Different Ethnic Groups

Diabetes is the world’s leading cause of renal and premature cardiovascular disease. There are marked differences between groups of patients with different ethnicities in their susceptibility to diabetes and its renal and cardiovascular complications. Novel markers of developing diabetes complications are related to disturbances in oxidative metabolism. In this cross-sectional study, we measured the arterial stiffness in patients of differing ethnicities with type 2 diabetes mellitus and assessed the relationship of their ethnicity with systemic markers of oxidative stress. Patients from black, African and Caribbean, and Asian minor ethnic groups were studied, with white patients with T2DM (n = 170) without evidence of cardiovascular disease (CVD). The vascular stiffness was measured by infrared finger-photoplethysmography. The oxidative stress burden was assessed by measuring the urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG), activities of plasma glutathione peroxidase (GPx-3), superoxide dismutase (SOD) activities, and concentration of selenium. The vascular stiffness and 8-OHdG were higher in the white than in the Black patients (9.68 m/s vs. 9.26 m/s, p = 0.021 and 292.8 ng/mL vs. 200.9 ng/mL, p = 0.0027, respectively). Meanwhile, the GPx-3 and SOD activities and selenium were lower in the white than in the Black patients (283.3 U/L vs. 440.4 U/L, p < 0.0001; 37.5 U/L vs. 75.6 U/L, p = 0.0007; and 1.14 vs. 1.28 µmol/L, p = 0.0001, respectively). In regression modelling, the 8-OHdG/creatinine ratio was an independent predictor of vascular stiffness in the white patient group (β = 0.23 m/s per unit increase in ln(8-OHdG/creatinine) [95% CI, 0.03 to 0.42]; p = 0.021) but not in the Black patient group (p = 0.29). Increased vascular stiffness, lower endogenous antioxidant defense, and greater levels of oxidative damage were found in patients of white ethnicity, which could contribute to the higher incidence of CVD compared with patients from Black minor ethnic groups with diabetic renal disease.