Glycated hemoglobin and lipid peroxidation in erythrocytes of diabetic patients

In diabetes, glycation and subsequent browning (or glycoxidation) reactions are enhanced by elevated glucose concentrations. It is unclear whether the diabetic state per se also induces an increase in the generation of oxygen -derived free radicals (OFRs), However, there is some evidence that glycati on itself may induce the formation of OFRs, OFRs cause oxidative damage to endogenous molecules, including cholesterol, 7-Oxocholesterol is known to b e one of the major products of cholesterol oxidation, The level of choleste rol peroxidation products was assessed in erythrocyte membrane lipid by mon itoring the peak height ratio of 7-oxocholesterol, one of the products of c holesterol peroxidation, to cholesterol with gas chromatography/mass spectr ometry (GC/MS), The peak height ratio of 7-oxocholesterol to cholesterol wa s used as a biomarker of lipid peroxidation. The hemoglobin Ale (HbA1c) val ue, an index of glycemic stress, was measured by high-performance liquid ch romatography, We examined the relationship between the levels of cholestero l peroxidation products and HbA1c in erythrocytes of diabetic and healthy s ubjects. There was a significantly increased ratio of 7-oxocholesterol to c holesterol in diabetic erythrocytes compared with control erythrocytes. The ratio of 7-oxocholesterol to cholesterol was significantly correlated with the level of HbA1c, This suggests that glycation of hemoglobin via chronic hyperglycemia is linked to cholesterol peroxidation in erythrocytes of bot h diabetic and healthy subjects. Copyright (C) 1999 by W.B. Saunders Compan y.