Increased resting and exercise-induced oxidative stress in young IDDM men

To assess the effect of acute physical exercise on oxidative stress and glutathione redox status and the relation to physical fitness in otherwise healthy young men with IDDM.

Nine men with IDDM (HbA1 7.3 +/- 1.7%), ages 21-30 years, and 13 matched control subjects exercised on a bicycle ergometer for 40 min at 60% of their maximal oxygen consumption (VO2max). Oxidative stress was assessed with plasma thiobarbituric acid reactive substance (TBARS) levels (an index of lipid peroxidation) and, in response to exercise, also glutathione redox status. For glutathione redox status, blood total glutathione (TGSH) and oxidized glutathione (GSSG) were determined. Blood samples were drawn immediately before and after exercise.

Resting plasma TBARS levels were markedly elevated in diabetic patients (2.2 +/- 0.7 vs. 0.9 +/- 0.4 mumol/l; P = 0.0002). Mean 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 GSSG/TGSH values. Exercise increased plasma TBARS and blood GSSG by approximately 50% in both groups. Resting plasma TBARS had a strong inverse correlation (r = -0.82; P = 0.006), and the exercise-induced percentage increase in TBARS had a strong positive correlation (r = 0.81, P = 0.008) with VO2max in diabetic subjects only.

Glutathione redox status appears to be adequate in healthy young moderately active diabetic men. On the other hand, they demonstrated increased resting and postexercise oxidative stress as indicated by plasma TBARS. Although exercise acutely induces oxidative stress, in patients with diabetes, physical fitness may have a protective effect against oxidative stress.