Relation between low-density lipoprotein cholesterol/apolipoprotein B ratio and triglyceride-rich lipoproteins in patients with coronary artery disease and type 2 diabetes mellitus: A cross-sectional study

Background: The low-density lipoprotein cholesterol/apolipoprotein B (LDL-C/apoB) ratio has conventionally been used as an index of the LDL-particle size. Smaller LDL-particle size is associated with triglyceride (TG) metabolism disorders, often leading to atherogenesis. We investigated the association between the LDL-C/apoB ratio and TG metabolism in coronary artery disease (CAD) patients with diabetes mellitus (DM). Methods: In the cross-sectional study, the LDL-C/apoB ratio, which provides an estimate of the LDL-particle size, was calculated in 684 consecutive patients with one additional risk factor. The patients were classified into 4 groups based on the presence or absence of CAD and DM, as follows: CAD (-) DM (-) group, n = 416; CAD (-) DM (+) group, n = 118; CAD (+) DM (-) group, n = 90; CAD (+) DM (+) group, n = 60. Results: A multi-logistic regression analysis after adjustments for coronary risk factors revealed that the CAD (+) DM (+) condition was an independent predictor of the smallest LDL-C/apoB ratio among the four groups. Furthermore, multivariate regression analyses identified elevated TG-rich lipoprotein (TRL)-related markers (TG, very-LDL fraction, remnant-like particle cholesterol, apolipoprotein C-II, and apolipoprotein C-III) as being independently predictive of a smaller LDL-particle size in both the overall subject population and a subset of patients with a serum LDL-C level < 100 mg/dL. In the 445 patients followed up for at least 6 months, multi-logistic regression analyses identified increased levels of TRL-related markers as being independently predictive of a decreased LDL-C/apoB ratio, which is indicative of smaller LDL-particle size. Conclusions: The association between disorders of TG metabolism and LDL heterogeneity may account for the risk of CAD in patients with DM. Combined evaluation of TRL-related markers and the LDL-C/apoB ratio may be of increasing importance in the risk stratification of CAD patients with DM. Further studies are needed to investigate the useful clinical indices and outcomes of these patients. Clinical Trial Registration UMIN (http://www.umin.ac.jp/)