Low-density lipoprotein (LDL) behavior after in vitro oxidation in three groups of diabetics

Diabetes is associated with increased morbidity and mortality resulting from cardiovascular disease. It has been established that oxidized LDLs are involved in the genesis of atherosclerosis. We have studied LDL oxidizability in three types of diabetics: insulin-dependent diabetes mellitus (IDDM), non-insulin-dependent diabetes mellitus (NIDDM) and insulin-treated diabetes mellitus type 2 (ITDM2) and a control group. LDLs have been isolated using ultracentrifugation and oxidized by addition of cupric chloride. With the oxidation kinetic, we calculated the lag time and the oxidation rate. Total fatty acids, alpha-tocopherol, and malondialdehyde (MDA) have been measured in native and oxidized LDLs. Diabetics have a significantly lower lag time and a lower level of alpha-tocopherol. Oxidized LDLs of diabetics show an important decrease of their polyunsaturated fatty acids with an increase of MDA compared to the control. Our study demonstrates a higher susceptibility to oxidation of LDL from diabetics; this can be explained by alteration in LDL composition or by the oxidative process occurring in this disease.