Background and aim: Type 2 diabetic patients have a greater prevalence of the metabolic syndrome, oxidative stress and accelerated atherosclerosis, compared to non-diabetics. We examined the association between biomarkers of lipid peroxidation and the presence of atherosclerosis and the metabolic syndrome in diabetic patients.
Methods and results: We studied oxidized LDL (OxLDL), OxLDL/LDL, OxLDL/HDL, lipoperoxides, autoantibodies against OxLDL (OxLDL-Ab), diene formation of LDL (lag phase), vitamin E, vitamin E/cholesterol and PON1 polymorphisms (-108C>T, 55T>A, and 192A>G) in 166 non-smoking type 2 diabetic patients, 119 fulfilling the criteria for the metabolic syndrome, 73 with atherosclerosis and 93 without atherosclerosis. Patients with macrovascular disease had higher values of OxLDL/LDL (11%; P=0.016), OxLDL/HDL (18%; P=0.024) and OxLDL-Ab (12%; P=0.046). OxLDL/LDL and OxLDL/HDL were correlated with the number of components of the metabolic syndrome (P<0.001). PON1 polymorphisms were not associated to LDL oxidation markers, only PON1 (-108TT) was weakly associated with higher OxLDL-Ab concentrations (22%; P=0.040) in patients with atherosclerosis.
Conclusion: OxLDL/LDL, OxLDL/HDL and OxLDL-Ab are the most useful clinical parameters of lipoprotein oxidation for discriminating the presence of macrovascular disease in diabetic patients. The presence of the metabolic syndrome in these patients is also associated with an increase in the oxidized lipoprotein ratios.