Composition of serum very-low-density and high-density lipoproteins in diabetes.

We examined the cholesterol/protein ratio and the apoprotein composition of serum lipoproteins in a randomly selected population of maturity-onset diabetics and in a group of nondiabetics of similar age. We found no differences in cholesterol distribution between the groups as a whole, but diabetics with above-normal low-density lipoproteins (LDL) had decreased concentrations of high-density lipoprotein (HDL) cholesterol. In the diabetics as a whole, there was an increase in the cholesterol/protein ratio in HDL, a negative correlation between the amounts of LDL cholesterol and HDL cholesterol, an increase in the proportion of apolipoprotein C in very-low-density lipoprotein (VLDL), and a decrease in the proportion of the apolipoprotein AI component of HDL. In diabetic subjects with increased VLDL, there was an increase in the relative amount of apolipoprotein CIII, and a consequent decrease in the ratio of apolipoprotein CII/apolipoprotein CIII in the VLDL. In both diabetic and control subjects, apolipoprotein E and cholesterol content of VLDL were linearly related.