Association between oxidant/antioxidant markers and proteinuria in type 2 diabetes: Results in 142 patients

Background: The relationship between oxidant/antioxidant markers and proteinuria in type 2 diabetes is not clear, partly because of the potentially confounding effect of renal function which tends to become impaired during the course of diabetes. Methods: We measured oxidized low-density lipoproteins (Ox-LDL), malondialdehyde (MDA) and extracellular superoxide dismutase (EC-SOD) in 142 type 2 diabetic patients (67 men). Renal function was assessed by plasma creatinine and glomerular filtration rate. Results: The group with proteinuria (n=78) was closely similar to the normoalbuminuric group (n=64) in age; body mass index; smoking habit; history of coronary artery disease; diabetes duration; use of lipid-lowering, antihypertensive and antidiabetic agents; blood pressure; fasting blood glucose; hemoglobin A1C and lipid profile. However, renal function was poorer and the proportion of males was higher in patients with proteinuria. When the effects of sex and renal function were controlled for, proteinuria was not a significant correlate of high Ox-LDL, but high MDA and EC-SOD levels were both significantly associated with proteinuria (p<0.01). Conclusions: There are significant associations, independent of renal function status, between proteinuria and MDA as well as between proteinuria and EC-SOD in type 2 diabetes.