The study was aimed at verifying how oxidative status varies with age of diabetes mellitus (DM) in sufferers with adequate blood sugar control. Forty-one diabetic otherwise healthy (DOH) volunteers and 57 apparently healthy controls were used and plasma levels of two endogenous antioxidant enzymes (Superoxide dismutase, SOD, and catalase, CAT) as well as two markers of oxidative damage (Malondialdehyde, MDA and erythrocyte osmotic fragility, EOF) were determined. Results obtained showed significant decreases in plasma SOD and CAT activities, and significant increases in plasma levels of MDA and EOF as age of disease increases. In addition, there were clear significant differences between the oxidative status of DOH and apparently healthy control subjects of similar chronological (birth) age group. Plasma MDA and EOF as markers of oxidative damage were significantly higher in DOH subjects compared with healthy control subjects of similar age. However, plasma SOD and CAT activities were observed to be significantly lower in DOH subjects compared with healthy control subject of comparable age. It could thus be concluded that diabetes is associated with progressive increase in tissue oxidative damage.