Metabolic control may influence the increased superoxide generation in diabetic serum

Superoxide anion (O₂^-) generation in serum from 10 Type 1 diabetic patients and 10 normal subjects was measured ex vivo. The amount of O₂^- production was significantly increased in diabetic serum 0.41 ± 0.04 (±SD) vs 0.14 ± 0.04 μmol l^-1 min^-1, p <0.001) and correlated with fasting plasma glucose and glycosylated protein levels in both diabetic (r = 0.72, p <0.01, and r = 0.62, p <0.05) and normal (r = 0.75, p <0.01 and r = 0.64, p <0.05) subjects. Improved metabolic control in the diabetic patients was associated with a reduction of serum O₂^- production (0.28 ± 0.06 μmol l^-1 min^-1, p <0.01), but the correlation between O₂^- levels and fasting plasma glucose and glycosylated protein concentrations was retained (r = 0.86 and r = 0.72, respectively, both p <0.01).