Increase in Total Antioxidant Capacity of Plasma despite High Levels of Oxidative Stress in Uncomplicated Type 2 Diabetes Mellitus

OBJECTIVE: Oxidative stress is implicated in the pathophysiology of diabetes mellitus and its chronic complications. The aim of this study was to evaluate plasma antioxidant status in patients with uncomplicated type 2 diabetes, in order to understand the interactions between its components and the diabetic milieu. METHODS: Plasma samples were collected from 15 patients with type 2 diabetes receiving oral antidiabetic agents and from 18 healthy control subjects without diabetes. Glycosylated haemoglobin was measured as an indicator of blood glucose control. Total and residual antioxidant activities were measured. Lipid peroxides were measured as indicators of plasma oxidative stress. Copper and caeruloplasmin were also assayed as possible pro-oxidants. RESULTS: Antioxidant activities, lipid peroxide level, copper concentration and caeruloplasmin activity were significantly increased in the plasma of patients with diabetes compared with control subjects. CONCLUSIONS: The total antioxidant capacity of plasma was increased, despite high levels of oxidative stress, in patients with uncomplicated type 2 diabetes. Increased levels of copper and caeruloplasmin characterized the diabetic milieu, despite an absence of chronic complications.