Lipid peroxidation and antioxidant enzyme levels in type 2 diabetics with microvascular complications

Serum levels of total cholesterol, triglycerides, lipoproteins, lipid perox ides (TBARS) and erythrocyte antioxidant enzyme activities were measured in 105 non insulin dependent diabetic patients, among whom 38 had microvascul ar complications (MVC) of diabetes. All the diabetic patients had higher co ncentrations of glycated hemoglobin (HbA1) compared to controls (10.51+/-2. 42% vs 6.31+/-0.85% P<0.001). Significant increase of serum triglycerides ( TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) an d very low density lipoprotein cholesterol (VLDL-C) and a significant decre ase of high density lipoprotein cholesterol (HDL-C) were observed in the di abetic patients compared to controls (TG: 2.31 +/- 0.9 mmol/l vs 1.53 +/- 0 .48 mmol/l P < 0.001; TC: 5.94 +/- 1.4 mmol/l vs 4.3 +/- 0.85 mmol/l P < 0. 001; LD L-C: 3.96 +/- 1.33 mmol/l vs 2.39 +/- 0.8 mmol/l P < 0.001; VLDL-C: 0.46 +/- 0.2 mmol/l vs 0.3 +/- 0.09 mmol/l P<0.001; HDL-C: 0.81 +/- 0.24 m mol/l vs 1.04 +/- 0.18 mmol/l P < 0.001). Significantly increased levels of serum TEARS were observed in diabetic patients compared to those in contro ls (TBARS: 6.7 +/- 1.5 mmol/l vs 5.14 +/- 0.61 mmol/l P < 0.001). Erythrocy te catalase (CAT) activity was increased and Glutathione peroxidase (GPx) a ctivity was decreased in diabetic patients compared to controls, but no sig nificant change in Superoxide dismutase (SOD) activity was observed in dia betic patients (CAT: 104.94 +/- 37.1 KU/g Hb vs 85.8 +/- 23.6 KU/g Hb, P < 0.01; GPx: 30 +/- 9.7 U/g Hb/min vs 40.84 +/- 12.3 U/g Hb/min, P < 0.001; S OD: 2.4 +/- 1.2 U/mg Hb/min vs 2.55 +/- 0.84 U/mg Hb/min, P=NS). in compari son with the diabetic group without MVC, the diabetic group with MVC had de creased GPx and SOD activities, while no difference was observed between th ese two groups regarding CAT activity (GPx: 25.32 +/- 8.4 U/g Hb/min vs 34. 5 +/- 8.8 U/g Hb/min, P < 0.001; SOD: 1.83 +/- 0.53 U/mg Hb/min vs 2.84 +/- 1.4 U/mg Hb/min, P<0.001; CAT: 106.3 +/- 39.9 KU/g Hb vs 103 +/- 34.9 KU/g Hb, P = NS). TEARS concentrations were significantly increased in the grou p with MVC compared to the group without these complications, indicating a positive relationship between TEARS and MVC of diabetes (7.05 +/- 1.23 mmol /l vs 6.3 +/- 1.02 mmol/l, P < 0.001). Serum triglycerides, LDI. and VLDL c holesterol concentration were significantly higher in diabetics with MVC th an in diabetics without the complications (TG: 2.7 +/- 0.98 mmol/l vs 2.13 +/- 0.82 mmol/l, P < 0.01; LDL - C: 4.45 +/- 1.3 mmol/l vs 3.67 +/- 1.3 mmo l/l, P < 0.02; VLDL-C: 0.53 +/- 0.19 mmol/l vs 0.43 +/- 0.16 mmol/l, P < 0. 01), and the serum levels of TC in the group with MVC showed a positive cor relation with their lipid peroxide levels (r= 0.368, P < 0.001). The increa se in TEARS and the decreased GPx and SOD activities in diabetics with MVC in this study indicate that these factors may contribute to the occurrence of micro vascular complications in NIDDM patients.