Evaluation of oxidative stress levels in obesity and diabetes by the free oxygen radical test and free oxygen radical defence assays and correlations with anthropometric and laboratory parameters

Background: Obesity and diabetes are associated with high levels of oxidative stress. In Romanian patients with obesity and (or) diabetes, this association has not been sufficiently explored.

Aim: To evaluate oxidative stress in obese and (or) diabetic subjects and to investigate the possible correlations between oxidative stress and anthropometric/biochemical parameters.

Methods: Oxidative stress was evaluated from a single drop of capillary blood. Reactive oxygen species (ROS) were evaluated using the free oxygen radical test (FORT). The free oxygen radical defence (FORD) assay was used to measure antioxidant levels.

Results: FORT levels were higher in obese subjects (3.04 ± 0.36 mmol/L H₂O₂) vs controls (2.03 ± 0.14 mmol/L H₂O₂) (P < 0.0001). FORD levels were lower in obese subjects (1.27 ± 0.13 mmol/L Trolox) vs controls (1.87 ± 1.20 mmol/L Trolox) (P = 0.0072). Obese diabetic subjects had higher FORT values (3.16 ± 0.39 mmol/L H₂O₂) vs non-diabetic counterparts (2.99 ± 0.33 mmol/L H₂O₂) (P = 0.0233). In obese subjects, FORT values correlated positively with body mass index (BMI) (r = 0.48, P = 0.0000), waist circumference (WC) (r = 0.31, P = 0.0018), fasting plasma glucose (FPG) (r = 0.31, P = 0.0017), total cholesterol (TC) (r = 0.27, P = 0.0068) and uric acid (r = 0.36, P = 0.0001). FORD values correlated negatively with BMI (r = -0.43, P = 0.00001), WC (r = -0.28, P = 0.0049), FPG (r = -0.25, P = 0.0130), TC (r = -0.23, P = 0.0198) and uric acid (r = -0.35, P = 0.0002). In obese diabetic subjects, FORT values correlated positively with BMI (r = 0.49, P = 0.0034) and TC (r = 0.54, P = 0.0217). FORD values were negatively associated with BMI (r = -0.54, P = 0.0217) and TC (r = -0.58, P = 0.0121).

Conclusion: Oxidative stress levels, as measured by the FORT and FORD assays, were higher in obese subjects vs controls. ROS levels were elevated in diabetic obese patients vs obese non-diabetic patients and controls.

Keywords: Antioxidants; Diabetes; Dyslipidaemia; Obesity; Oxidative stress; Reactive oxygen species.