Age-independent oxidative stress in elderly patients with non-insulin-dependent diabetes mellitus

Impaired antioxidant defence is implicated in the development of cardiovasc ular complications in non-insulin-dependent diabetes (NIDDM). However, as m any of these patients are elderly, observed changes in antioxidant status m ay be due to the patient's age rather than their disease. We sampled blood from 47 elderly NIDDM patients (21 male and 26 female; mean age +/- SD 75.6 2+/-7.97 years), 66 young (30 male and 36 female; 24.52 +/-4.72 years) and 58 healthy elderly volunteers (17 male and 41 female; 70.74+/-4.85 years), and measured the antioxidant glutathione, the marker for free-radical-damag e lipid hydroperoxide products (LHP), vitamin E and total antioxidant capac ity) (TAC). There was a significant increase in LHP in the healthy elderly group compared with the young volunteers (3.14 +/-1.5 vs. 2.14+/-1.38 mu mo l/l, p<0.01). The values were much higher in NIDDM patients (7.02 +/- 2.29 mu mol/l, p<0.0001 vs. healthy elderly). There was a reduction in TAC in he althy elderly compared with the young (359.99 +/-154.82 vs. 471.47 +/- 94.2 9 mu mol/l trolox equivalents, p< 0.0001), but there was no further reducti on in NIDDM patients. Similarly, glutathione was reduced to the same degree in healthy elderly and NIDDM patients (0.29+/-0.09, 0.30+/-0.11 vs. 0.54 0 .19 mu mol/l in young volunteers, p<0.0001). Vitamin E concentrations were comparable in all groups (26.34+/-5.39 young volunteers, 31.50 +/-8.23 heal thy elderly and 30.98+/-9.03 mu mol/l NIDDM patients), but after correction for serum cholesterol there was a significant reduction in the diabetic gr oup compared with the young, but not with the elderly (5.54 +/-1.55 vs. 6.6 7 +/-1.86 vs. 6.31 +/-1.85 (mu mol/l)/(mmol/l), p<0.01). We have demonstrat ed an age-dependent reduction in total antioxidant capacity and glutathione defence and an age-independent increase in LHP in elderly patients with NI DDM. Reduced concentrations of vitamin E were demonstrated in NIDDM patient s compared with young, but not elderly, volunteers. Increased oxidative dam age occurs independently of age in NIDDM patients despite comparable antiox idant defences in this age group.