Abstract Objective: To evaluate the effect of diabetes mellitus and its chronic complications on thiol/disulfide homeostasis. Methods: The study included 381 participants divided into six groups: healthy controls (Group 1; n = 91), patients with prediabetes (Group 2; n = 50), patients with diabetes mellitus without complications (Group 3; n = 70), patients with diabetic retinopathy (Group 4; n = 47), patients with diabetic nephropathy (Group 5; n = 70), and patients with diabetic foot (Group 6; n = 53). […]