Plasma 8-Hydroxy-2′-Deoxyguanosine Levels in Patients with Type 2 Diabetes Mellitus

Background/Objectives: Type 2 diabetes mellitus (T2DM) is a complex metabolic disorder characterized not only by impaired carbohydrate metabolism but also by alterations in lipid and protein metabolism. Hyperglycaemia in T2DM can promote the excessive production of reactive oxygen species (ROS), leading to oxidative stress. 8-Hydroxy-2′-deoxyguanosine (8-OHdG) is a biomarker of oxidative DNA damage commonly used to investigate oxidative stress. Methods: In this cross-sectional analytical observational study, patients diagnosed with T2DM and healthy controls were enrolled. Plasma 8-OHdG concentrations were measured using an enzyme-linked immunosorbent assay (ELISA). Associations between 8-OHdG concentrations and age, fasting blood glucose, and lipid profile parameters were evaluated. These associations were further explored in patient subgroups defined according to glycated haemoglobin (HbA1c) levels. Results: Patients with T2DM had higher plasma 8-OHdG concentrations than healthy controls (Cohen’s d = 1.092; 95% CI, 0.646–1.532; p < 0.001). After adjustment for age, the between-group difference was attenuated, with an adjusted mean difference of 28.84 ng/mL (95% CI, 0.278–57.41; p = 0.048). In the overall cohort, statistically significant correlations were identified between 8-OHdG levels and age (ρ = 0.379; 95% CI, 0.164–0.556; p < 0.001), fasting blood glucose (ρ = 0.266; 95% CI, 0.059–0.474; p = 0.011), and triglycerides (ρ = 0.376, 95% CI, 0.178–0.554; p < 0.001). Stratification of patients according to HbA1c levels revealed no statistically significant differences in 8-OHdG concentrations among the subgroups. Furthermore, none of the correlations examined within these subgroups remained statistically significant after adjustment for multiple testing. Conclusions: Plasma 8-OHdG concentrations were higher in patients with T2DM than in healthy controls, although the magnitude of the between-group difference was attenuated after adjustment for age. In the overall study population, 8-OHdG concentrations were associated with age, fasting blood glucose, and triglyceride concentrations. These findings suggest that 8-OHdG levels may be associated with demographic and metabolic factors. Given the cross-sectional design, these associations should not be interpreted as causal. Further prospective studies with larger cohorts are needed to evaluate the potential clinical relevance of plasma 8-OHdG measurement in T2DM.