Diabetes mellitus (DM) is a common global metabolic disease. Oxidative stress from reactive oxygen species (ROS) contributes to its development and leads to complications like heart disease, kidney failure, and stroke. Chronic inflammation in diabetes is associated with insulin resistance and elevated glucose levels, as indicated by increased markers of interleukin-6 (IL-6), C-reactive protein (CRP), and tumor necrosis factor-alpha (TNF-α). This study investigates the activity and concentration of antioxidant enzymes (SOD, GPX1, CAT) and inflammatory markers (IL-6, CRP, TNF-α) in patients with type 1 and type 2 diabetes compared to healthy controls. The study included 73 patients-33 with type 1 diabetes (18 men, 15 women) and 40 with type 2 diabetes (20 men, 20 women)-and 41 healthy controls (23 men, 18 women). Antioxidant enzymes and inflammatory markers were measured using enzyme-linked immunosorbent assay (ELISA), and HbA1c levels were assessed. Program R and Statistica 13 were used to analyze the results. Group membership had a significant impact on SOD and CAT activity (p < 0.0001) and GPX1 (p < 0.001). BMI correlated with CAT concentration (p < 0.0001). SOD activity was affected by comorbidities, such as arthritis and urinary tract issues (p = 0.03). Diabetes markedly altered inflammatory markers, particularly CRP and TNF-α (p < 0.0001), and higher IL-6 levels were found in patients using medications other than metformin (p = 0.01). Type 1 and 2 diabetes significantly affect antioxidant enzyme activity and concentration. High SOD and GPX activity suggests chronic oxidative stress, while increased BMI is linked to lower enzyme levels. Additionally, TNF-α levels rise with diabetes duration, which may serve as a biomarker for disease progression and complications, potentially helping to predict diabetic complications and insulin resistance.