The Association between the Triglyceride to High-density Lipoprotein Cholesterol Ratio and Low-density Lipoprotein Subclasses

OBJECTIVE: The triglyceride (TG)/high-density lipoprotein cholesterol (HDL-C) ratio is related to insulin resistance (IR). However, information about whether or not the TG/HDL-C ratio is associated with low-density lipoprotein (LDL) subclasses in the Japanese population is limited. METHODS: In total, 1,068 Japanese subjects who underwent an annual health examination and who were not taking medications were recruited. The association between the TG/HDL-C ratio and LDL subclasses was investigated using correlation, multiple regression, and receiver operating characteristic analyses. RESULTS: A correlation analysis revealed that both malondialdehyde-modified low-density lipoprotein (MDA-LDL) and small dense low-density lipoprotein cholesterol (sdLDL-C) were positively associated with the TG/HDL-C ratio. Furthermore, a multiple linear regression analysis revealed that the TG/HDL-C ratio was positively associated with MDA-LDL and sdLDL-C in both men and women. The multiple logistic regression analysis also revealed that the TG/HDL-C ratio was positively associated with the upper tertile of MDA-LDL and sdLDL-C in men and women. The LDL-C levels increased with the increasing TG/HDL-C ratio. The MDA-LDL and sdLDL-C are known to be positively associated with LDL-C. However, within the same LDL-C range, both MDA-LDL and sdLDL-C levels increased with the TG/HDL-C ratio, except for MDA-LDL levels in the LDL-C <112 mg/dL group in women. These results further supported the notion that the TG/HDL-C ratio was positively associated with the MDA-LDL and sdLDL-C levels, especially in the higher LDL-C range, in both men and women. The optimal cut-off points of the TG/HDL-C ratio for the upper tertile of MDA-LDL and sdLDL-C were 1.85 and 2.03 in men and 0.88 and 1.30 in women, respectively. CONCLUSION: The TG/HDL-C ratio is positively associated with MDA-LDL and sdLDL-C in Japanese subjects. The relationship was particularly notable in subjects with high LDL-C levels.