In this study, we aimed to examine dynamic thiol/disulfide homeostasis in type 1 diabetes mellitus (T1DM) and identify the factors associated with thiol oxidation. Thirty-eight subjects (18 male, 20 female) diagnosed with T1DM and 38 (17 male, 21 female) healthy volunteers without any known diseases were included in the study. Thiol/disulfide homeostasis concentrations were measured by a newly developed method (Erel & Neselioglu) in this study. After native thiol, total thiol and disulfide levels were determined; measures such as disulfide/native thiol, disulfide/total thiol, and native thiol/total thiol were calculated. In T1DM patients, compared to the control group, disulfide (p = 0.024), disulfide/native thiol (p < 0.001), and disulfide/total thiol (p < 0.001) were determined higher, while native thiol (p = 0.004) and total thiol (p < 0.001) levels were much lower. In the patient group, a positive correlation was determined between c-reactive protein (r = 325, p = 0.007; r = 316, p = 0.010, respectively), fasting blood glucose (r = 279, p = 0.018; r = 251, p = 0.035, respectively), and glycosylated hemoglobin (r = 341, p = 0.004; r = 332, p = 0.005, respectively) and rates of disulfide/native thiol and disulfide/total thiol. We determined that thiol oxidation increase in T1DM patients compared to the control group. We thought that hyperglycemia and chronic inflammation might be the major cause of increase in oxide thiol form. In order to determine the relationship between the status of autoimmunity and dynamic thiol/disulfide in T1DM, dynamic thiol/disulfide homeostasis in newly diagnosed-antibody positive-T1DM patients is required to be investigated.