Abnormal lipoprotein composition in normolipidemic diabetic patients.

To see whether there are any lipoprotein abnormalities in diabetic patients without hyperlipidemia, lipoprotein composition was examined in 75 strictly normolipidemic diabetic patients. Their plasma cholesterol (chol) and triglyceride (TG) were limited to less than 6.0 and less than 1.7 mM, respectively. Body-weight- and age-adjusted normolipidemic healthy subjects served as the control group. Plasma total chol and TG and low-density lipoprotein (LDL-) and high-density lipoprotein (HDL-) chol were identical in the diabetic and control subjects. Total apolipoprotein B (apoB) in the plasma of the diabetic subjects was significantly elevated. The chol-apoB ratio in the TG-rich (very-low-density + intermediate-density) lipoprotein fraction (Sf12-400) of the diabetic subjects was significantly higher than the control value, whereas LDL-apoB levels were increased and chol-apoB ratio in the LDL fraction was significantly suppressed in the diabetic subjects. Because each LDL particle contains only one apoB molecule, apoB and chol-apoB ratio in this fraction can represent particle number and chol loading of the LDL particles, respectively. Thus, these data suggest that LDL particle number is increased, and the particles are chol depleted in diabetic subjects even if they are normolipidemic.