Paraoxonase-1, malondialdehyde and glutathione reductase in Type 2 Diabetic patients with nephropathy

Numerous experimental and epidemiologic studies shown that oxygen-free-radicals are elevated in uncontrolled diabetes mellitus (DM). Paraoxonase-1 (PON1) has been reported to confer antioxidant activities by decreasing the accumulation of lipid peroxidation products. This study was designed to investigate the role of PON1 activity, glutathione reductase (GR), and lipid peroxidation in patients with diabetic nephropathy (DN). 70 subjects were included in the study: 30 as a control, 20 with type 2 DM (T2DM) with nephropathy (DN), 20 T2DM without nephropathy. All studied groups are subjected to the following laboratory investigations after their consents: fasting and postprandial blood glucose, Serum triglycerides (TG), total cholesterol (TC), high density lipoprotein (HDL) and low density lipoprotein (LDL), HbA1c, blood urea, serum creatinine, urine microalbumin, serum PON1 activity, serum malondialdehyde (MDA), and serum GR activity. Fasting and postprandial blood glucose levels, and HbA1c was significantly higher in the DN group than the diabetic or control group (p=0.0001). Serum creatinine show a significant rise in the DN group than diabetic or control group (p=0.0001). Microalbuminuria show a significant rise in the DN group than the control or diabetic group as well as in the diabetic group than control group (p=0.0001). Serum PON1 activity and GR level showed significant decrease in diabetic patients with or without nephropathy compared to the control group with a significant decrease in its activity in the DN group while there was a significant a rise of MDA in diabetic groups than control with a significant rise in DN. The decreased antioxidant enzyme activities in DN patients, suggesting that oxidative stress may contribute to the development of DN and other microvascular complications beside chronic hyperglycemia and dyslipidemia. Measurement of PNO1, MDA and GR levels may be a helpful marker in the diagnosis and follow up DN.