Comparative analysis of plasma and erythrocyte 7-ketocholesterol as a marker for oxidative stress in patients with diabetes mellitus

Objectives: To reveal increased lipid peroxidation in diabetics by quantifi cation of cholesterol oxidation products (COPs) not only in plasma, but als o in erythrocytes. Design and methods: We quantified 7-ketocholesterol (7-kCho) by gas chromat ography-mass spectrometry as a surrogate measure for COPs. These assays wer e performed on both plasma and erythrocytes in 20 control subjects and 20 t reated patients with relatively poorly controlled Type 2 diabetes. Results: Both plasma and erythrocyte 7-kCho levels in diabetics were signif icantly higher than those in control subjects. Although neither plasma nor erythrocyte 7-kCho levels were associated with markers for glucose toleranc e in diabetics, a negative correlation of serum HDL-cholesterol levels with erythrocyte, but not plasma, 7-kCho levels was found. Conclusion: Increased oxidative stress in diabetics affects oxidation of ch olesterol. Assays of COPs not only in plasma, but also in erythrocytes, may yield complementary information in lipid peroxidation. Copyright (C) 2000 The Canadian Society of Clinical Chemists.