ANTIOXIDANT STATUS IN PATIENTS WITH UNCOMPLICATED INSULIN-DEPENDENT AND NON-INSULIN-DEPENDENT DIABETES-MELLITUS

Oxidative damage by free radicals has been implicated in the pathogene sis of vascular disease in diabetes. We compared the radical-scavengin g antioxidant activity of serum from 28 patients with insulin-dependen t diabetes mellitus and 24 patients with noninsulin-dependent diabetes mellitus uncomplicated by vascular disease with age-matched non-diabe tic control subjects. Patients with insulin-dependent diabetes had sig nificantly reduced total antioxidant activity (320.2 +/- 11.3 vs. 427. 5 +/- 19.2 mu mol L-1; P < 0.001). This was attributable to lower urat e (209.4 +/- 10.4 vs. 297.1 +/- 16.7 mu mol L-1; P < 0.001) and vitami n C levels (63.6 +/- 6.0 vs. 87.5 +/- 4.9 mu mol L-1; P < 0.01). Patie nts with non-insulin-dependent diabetes had lower total antioxidant ac tivity than age-matched control subjects (433.8 +/- 25.4 vs. 473.9 +/- 30.2 mu mol L-1; NS), reflecting lower urate (299.5 +/- 19.4 vs. 324. 8 +/- 21.4 mu mol L-1; NS) and vitamin C levels (38.6 +/- 5.7 vs. 58.5 +/- 5.3 mu mol L-1; P < 0.05). Multiple regression analysis showed th at urate, vitamin C and vitamin E were the major contributors to serum total antioxidant activity. These results show that diabetic patients have significant defects of antioxidant protection, which may increas e vulnerability to oxidative damage and the development of diabetic co mplications.