Quantitative and qualitative alterations of plasma lipoproteins in obesity

: In order to clarify lipoprotein abnormality in mild to moderate obesity (BMI > or = 25), plasma was separated by table top ultracentrifugation into VLDL (chylomicron), IDL, LDL and HDL. Chol, TG and ApoB were determined in each fraction by enzymatic and sensitive Latex method. The data were analysed according to glucose intolerance and hyperinsulinemia (HI). In obese subjects, irrespective of glucose intolerance, Chol, TG & ApoB levels were high in plasma, and an increase in VLDL (Chol, TG & ApoB), IDL (Chol & ApoB), LDL (Chol & ApoB), and a decrease in HDL-Chol were observed. These levels were also abnormal in nonDM particularly with HI. In DM, HI did not seem to affect hyperlipidemia. Correlation between Chol, TG and ApoB in three ApoB containing lipoprotein subfractions was noted in obesity. The ratio of Chol/ApoB and TG/ApoB in LDL was significantly lower in obesity implying that LDL particles were smaller in size. Half of nonDM patients had HI, and only 29% of DM patients had HI, and both groups had almost the same lipoprotein abnormality. Hyperlipidemia was severe in nonDMHI(+) compared to nonDMHI(-). Therefore, in hyperlipidemia of obesity, hyperinsulinemia plays a role in nonDM and hyperglycemia in DM. Insulin resistance seems to be an important factor in DM. Although the mechanism may be different, the consequence of hyperlipidemia is similar. Increased numbers of ApoB containing lipoproteins and smaller size of LDL are the characteristic features of hyperlipidemia in mild to moderate obesity. Because these quantitative and qualitative changes appear to be linked to an increased risk for premature arteriosclerosis, intensive therapy should be recommended even in mild to moderate obesity.