Mutation Research 638 (2008) 98–102 Available online at www.sciencedirect.com Oxidative DNA damage and plasma antioxidant capacity in type 2 diabetic patients with good and poor glycaemic control Maura Lodovici a,∗ , Lisa Giovannelli a , Vanessa Pitozzi a , Elisabetta Bigagli a , Gianluca Bardini b , Carlo Maria Rotella b a Department of Pharmacology, University of Florence, Viale Pieraccini 6, 50139 Florence, Italy b Department of Clinical Physiopathology, University of Florence, Viale Pieraccini 6, 50139 Florence, Italy Received 22 May 2007; received in revised form 31 August 2007; accepted 7 September 2007 Available online 14 September 2007 Abstract Diabetes mellitus is a complex metabolic disorder characterized by a disturbance in glucose metabolism. Recent evidence suggests that increased oxidative damage as well as reduction in antioxidant capacity could be related to the complications in patients with type 2 diabetes. The aim of this study was to measure plasma antioxidant status in type 2 diabetic patients with good and poor glycaemic control and its relationship with oxidative DNA damage. Thirty-nine type 2 diabetic patients and eighteen healthy subjects were recruited for this study. We found that diabetic patients had slightly, but not significantly lower antioxidant capacity, measured with the “ferric reducing ability of plasma” (FRAP) assay, than healthy subjects. On the contrary, oxidative DNA damage (measured by the Comet assay) in leukocytes obtained from diabetic patients was significantly higher compared to healthy subjects. Taking into account glucose control, we found that the FRAP level was significantly (p < 0.05) lower in diabetic subjects with poor glycaemic control than healthy subjects, while patients with good glycaemic control had FRAP values similar to controls. We also observed an unexpected positive correlation between FRAP values and oxidative DNA damage in diabetic patients; moreover, a positive correlation was found between FRAP and glucose level or HbA 1c in patients with poor glycaemic control. In conclusion, our results confirm that patients with type 2 diabetes have a higher oxidative DNA damage than healthy subjects and that plasma antioxidant capacity is significantly lower only in patients with poor glycaemic control, moreover, in these patients FRAP values are positively correlated with glycaemic levels and HbA 1c . These observations indicate that a compensatory increase of the antioxidant status is induced as a response to free radical overproduction in type 2 diabetes. Therefore, the addition of antioxidant supplements to the current pharmacological treatment could have potentially beneficial effects in diabetic patients with poor glycaemic control. © 2007 Elsevier B.V. All rights reserved. Keywords: Oxidative DNA damage; Comet assay; FRAP; Diabetes 1. Introduction Type 2 diabetes mellitus is one of the most com- mon metabolic diseases, affecting about 3% of the ∗ Corresponding author. Tel.: +39 055 4271 321; fax: +39 055 4271 280. E-mail address: maura.lodovici@unifi.it (M. Lodovici). human population [1]. Clinically, it is a heteroge- neous disease, characterized by metabolic disorders, defective blood glucose control and is frequently associ- ated with chronic complications such as lens cataracts, nephropathy, neuropathy and cardiovascular diseases [2]. Hyperglycaemia in itself, often present in diabetic patients, causes the autoxidation of glucose, glycation of proteins and the activation of polyol metabolism. These changes accelerate the generation of reactive 0027-5107/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.mrfmmm.2007.09.002