Relationship between total oxidant status and severity of diabetic nephropathy in type 2 diabetic patients

Background and aim: Data on oxidative stress in type 2 diabetic patients with diabetic nephropathy is scant. The objective of this study was to investigate possible associations between total oxidant status (TOS) and the severity of diabetic nephropathy in type 2 diabetic patients by using a novel automated measurement method. Methods and results: Thirty-six patients with diabetic nephropathy (group 1), 25 diabetic patients without nephropathy (group 2) and 30 controls (group 3) were enrolled. Serum total antioxidant capacity (TAC), TOS levels and oxidative stress index (OSI) were determined. The severity of the disease was determined with microalbuminuria levels. TAC was lower, while TOS and OSI were higher in group 1 than in group 3 (P < 0.01, P < 0.001, P < 0.001; respectively). There were no statistically significant differences between group 2 and group 3 with respect to TAC, TOS and OSI (all P > 0.05). Group 1 had higher TOS and OSI than group 2 (both P < 0.05), but there was no statistically significant difference with respect to TAC. Significant correlations were observed between microalbuminuria levels, and TAC, TOS and OSI levels (r = -0.616, P < 0.001; r = 0.488, P < 0.01; r = 0.567, P < 0.001; respectively). Conclusion: Our results suggest that oxidative stress is increased in patients with diabetic nephropathy compared to diabetic patients without nephropathy and this increase seems to be related to the severity of microalbuminuria levels. (c) 2006 Elsevier B.V. All rights reserved.