Oxidative stress has been involved in the pathogenic process of a variety of diseases including diabetes mellitus. The production of oxidative reactive products has been involved in biochemical changes in bio-molecules that might produce tissue damage directly related to some of the main vascular complications in the diabetic patient. On the other hand, exercise, paradoxically, is a well-recognized model of oxidative stress and also an important therapeutic tool in diabetes management. Therefore, the relationship between oxidative stress and exercise in diabetic patients implies an interesting biochemical paradox due to some of the negative effects of exercise principally by the increase of oxidative species in plasma. The effect of oxidative stress during an acute exercise and after an aerobic training period on those patients remains unknown and needs to be studied.