Effect of gemfibrozil on high density lipoprotein subspecies in non-insulin dependent diabetes mellitus. Relations to lipolytic enzymes and to the cholesteryl ester transfer protein activity.

Twenty patients (18 men, 2 women) with non-insulin dependent diabetes mellitus (NIDDM) were randomized to receive either gemfibrozil 1200 mg daily or placebo for 3 months in a double-blind study. The effect of gemfibrozil on plasma HDL subfraction distribution was studied with sequential and density gradient ultracentrifugation and in gradient gel electrophoresis. The concentrations of apo A-I, apo A-II, Lp A-I and Lp A-I:A-II particles were measured. Postheparin plasma lipoprotein lipase (LPL) and hepatic lipase (HL) activities and plasma cholesteryl ester transfer protein (CETP) activities were also determined. Gemfibrozil increased the concentration of HDL cholesterol (P < 0.01), which was due to the rise of HDL3 cholesterol (+16%), while in the placebo group these values remained unchanged. Gemfibrozil increased the concentrations of apo A-I(+12.6%, NS), apo A-II (+28.2%, P < 0.01) and Lp A-I:A-II particles (+21.6%, P < 0.06) but there were no changes in the placebo group. Neither gemfibrozil nor placebo had any effect on the concentration of Lp A-I particles. As determined by density-gradient ultracentrifugation, gemfibrozil increased the concentration of cholesterol in the most dense HDL fractions (mean density 1.193 g/ml, +22%, P < 0.05 and mean density 1.158 g/ml, +19.3%, P < 0.05). In gradient gel electrophoresis, the gemfibrozil-induced elevations of the cholesterol and protein were most pronounced in the HDL3a (8.8-8.2 nm) region. Gemfibrozil increased LPL and HL activities by 14.7% (P < 0.05) and by 18.8% (P < 0.01), respectively, while in the placebo group LPL and HL activities remained unchanged. Plasma CETP activity was also increased during gemfibrozil treatment while in the placebo group it remained unchanged. We conclude that gemfibrozil causes multiple changes in plasma HDL metabolism. The gemfibrozil-induced elevation of HDL3 and dense HDL subpopulations may reflect the concerted action of LPL, HL and CETP on plasma HDL metabolism.