INCREASED RESTING AND EXERCISE-INDUCED OXIDATIVE STRESS IN YOUNG IDDMMEN

OBJECTIVE - To assess the effect of acute physical exercise on oxidati ve stress and glutathione redox status and the relation to physical fi tness in otherwise healthy young men with IDDM. RESEARCH DESIGN AND ME THODS - Nine men with IDDM (HbA(1c) 7.3 +/- 1.7%), ages 21-30 years, a nd 13 matched control subjects exercised on a bicycle ergometer for 40 min at 60% of their maximal oxygen consumption (Vo(2max)). Oxidative stress was assessed with plasma thiobarbituric acid reactive substance (TEARS) levels (an index oi lipid peroxidation) and, in response to e xercise, also glutathione redox status. For glutathione redox status, blood total glutathione (TGSH) and oxidized glutathione (GSSG) were de termined. Blood samples were drawn immediately before and alter exerci se. RESULTS - Resting plasma TEARS levels were markedly elevated in di abetic patients (2.2 +/- 0.7 vs. 0.9 +/- 0.4 mu mol/l; P = 0.0002), Me an blood TGSH was higher in diabetic subjects (1,203 +/- 221 vs. 936 /- 156 mmol/l; P = 0.002), with no significant difference in GSSG or G SSG/TGSH values. Exercise increased plasma TEARS and blood GSSG by sim ilar to 50% in both groups. Resting plasma TEARS had a strong inverse correlation (r = -0.82; P = 0.006), and the exercise-induced percentag e increase in TEARS had a strong positive correlation (r = 0.81), P = 0.008) with VO2max in diabetic subjects only. CONCLUSIONS - Glutathion e redox status appears to be adequate in healthy young moderately acti ve diabetic men. On the other hand, they demonstrated increased restin g and postexercise oxidative stress as indicated by plasma TEARS. Alth ough exercise acutely induces oxidative stress, in patients with diabe tes, physical fitness may have a protective effect against oxidative s tress.