ACCELERATED CHOLESTERYL ESTER TRANSFER IN NONINSULIN-DEPENDENT DIABETES-MELLITUS

Alterations in core lipid composition of lipoproteins in noninsulin-dependent diabetes mellitus (NIDDM) patients have suggested that the heteroexchange of neutral lipids between HDL and the apo B-containing lipoproteins may- be enhanced. For this reason, we studied cholesteryl ester transfer (CET) in ten sulfonylurea-treated patients with stable NIDDM. CET measured in all NIDDM subjects with an assay of mass transfer was significantly greater than that of controls at 1 and 2 h (P < 0.001); the transfer of radiolabeled CE also was increased in a subset of four of the NIDDM group (NIDDM k = 0.21 +/- 0.04 vs. control k = 0.10 +/- 0.05;P < 0.05). A weak correlation was demonstrable between the mass of CE transferred at 1 h and diabetic control expressed as plasma fructosamine (r = 0.58, P < 0.09). To characterize this disturbance in C;ET further, the donor (HDL + VHDL) and acceptor (VLDL + LDL) lipoprotein fractions were isolated by ultracentrifugation at d 1.063 g/ml from NIDDM and control plasma and a series of recombination experiments were performed. Combining NIDDM acceptor with control donor fractions that contained HDL and CETP and not the combination of NIDDM donor and control acceptor lipoproteins resulted in an accelerated CET response identical to that observed in NIDDM whole plasma. This observation indicated that the abnormality in CET in NIDDM was associated with the VLDL + LDL fraction. To discern which lipoprotein class was dysfunctional, VLDL (d < 1.006 g/ml) and LDL (d 1.006-1.063 g/ml) from NIDDM and control subjects were isolated and combined with the d > 1.063 g/ml fractions of their respective control at the same triglyceride concentration for VLDL and cholesterol for LDL. These experiments revealed that NIDDM VLDL and not LDL promoted CET. Concentrations of cholesteryl ester transfer protein (CETP) did not differ in the two groups (NIDDM 1.63 +/- 0.36 mu g/ml vs. control 1.33 +/- 0.36). These findings indicate that CET is increased in the plasma of NIDDM patients, and this abnormality appears to result from dysfunction of VLDL. Since this abnormality may promote the generation of increased numbers of potentially atherogenic cholesteryl ester-enriched apo B-containing lipoproteins, it may be a previously unrecognized risk factor that contributes to the development of macrovascular complications in NIDDM.