Small dense LDL particles (sdLDL), with greater suceptibility to oxydation, are well-recognized risk marker for coronary artery disease (CAD) and type 2 diabetes mellitus. The aim of the present study sought to separate sdLDL subfraction by heparin-magnesiun precipitation method and to evaluate the possible association of low-density lipoprotein (LDL) particle size CAD and type 2 diabetes mellitus.

Forty eight CAD (with or without type 2 diabetes mellitus) patients and 51 apparently healthy subjects were included in this study. sdLDL-cholesterol (sdLDL-C) measured after heparin-magnesiun precipitation. LDL-Cholesterol (LDL-C) was calculated by the Friedwald formula and large, buoyant LDL-Cholesterol (lrgLDL-C) was estimated by subtraction.

The prevalence of sdLDL was strongly related with the CAD risk level. However, large, buoyant LDL-C showed no significant decrease in CAD patients. LDL-C decreased significantly in CAD without diabetes (CADd-) when compared to controls. Its level significantly lower in CAD with diabetes (CADd+) patients with respect to healthy and to CADd-patients. Small density LDL-C increased significantly in coronary patients (with or without diabetes). However, lrgLDL-C was significantly decreased only in (CADd+) group compared to controls (0.73±0.02 vs 2.02±0.04; p= 0.03 respectively). A negative correlation (r=–0.22, p=0.03) between TG and sdLDL-C levels was observed when all groups are geathred, and was not found in controls and CAD patients (with or without diabetes). No correlation could be evidenced between HDL-C and sdLDL-C concentrations in all groups nor in CAD group.

elevated sdLDL-C level may contribute to atherosclerosis that renforce the developement of coronaropathy. The decrease of lrgLDL seems to be attribuated to diabetes mellitus rather than to CAD.