Effects of dietary cholesterol on plasma lipoproteins and their subclasses in IDDM patients

To compare the effects of dietary cholesterol supplementation in insulin-dependent diabetic (IDDM) patients and normal subjects, 10 male IDDM patients in good glycaemic control (HbA1c 7.3+/-0.9%) (mean+/-SD) and normal plasma lipid levels, and 11 control male subjects of similar age, body mass index and lipid plasma levels underwent a double blind, cross-over, sequential study. Cholesterol supplementation of 800 mg/day or placebo were given for consecutive periods of 3 weeks. The concentration of plasma total cholesterol increased significantly with the dietary cholesterol supplementation compared to placebo in IDDM patients by 6% (p < 0.05) and in control subjects by 9% (p < 0.05). No changes were observed in the concentration of plasma triglycerides in either group. The LDL cholesterol level increased by 12% (p < 0.01) in patients and by 7% (p < 0.05) in control subjects. In patients plasma HDL cholesterol concentration remained the same, while in control subjects it tended to increase after cholesterol supplementation (from 1.14+/-0.26 to 1.23+/-0.27 mmol/l, p = 0.06). During the cholesterol intake period the mean concentration of LDL1, LDL2 and LDL3 subclasses in patients showed a significant increase by 21.0 (p < 0.05), 20.4 (p < 0.001) and 11.1% (p < 0.05), respectively, resulting in an 18.0% increase in mean total LDL mass (p < 0.001) without major changes in LDL composition. In the control subjects the changes in the concentrations of LDL subclasses during cholesterol intake were less and not significant. In the IDDM patients the cholesterol intake did not affect the concentration or composition of HDL subclasses or total HDL mass. In contrast, in control subjects cholesterol intake increased the mean concentration of HDL2a by 12.2.% (p < 0.05) and this increase was significantly different if compared to changes obtained in the patients. In conclusion, compared to normal subjects, in IDDM patients, dietary cholesterol intake increased the LDL particle mass significantly and had no positive effect on HDL.