AIMS
Patients with type 2 diabetes mellitus (T2DM) typically exhibit a reduction in LDL-particle size. LDL-cholesterol (LDL-C) to Apolipoprotein B (ApoB) ratio is an accessible and reliable proxy for the LDL-particle size. However, whether the prognostic value of LDL-C/ApoB ratio differs between diabetic and nondiabetic populations remains unclear. The aim of the present study was to investigate whether T2DM modulates the prognostic value of LDL-C/ApoB ratio in statin-treated patients with coronary artery disease (CAD) undergoing percutaneous coronary intervention (PCI).

METHODS AND RESULTS
The study included 21,382 CAD patients undergoing PCI who had received statin therapy at baseline with a median follow-up of 3.1 years. The primary endpoint was major adverse cardiac events (MACE), including all-cause mortality, non-fatal myocardial infarction (MI), and ischemia-driven revascularization. In the present study, we used LDL-C/ApoB ratio to represent LDL particle size. According to previous study, patients were assigned into 2 groups according to the LDL-C/ApoB cutoff value of 1.20.
The mean age was 59.67±10.11 years and 76.66% was male. A total of 9360 (43.78%) patients had T2DM at baseline. Higher LDL-C/ApoB level (≥1.20) was associated with a decreased risk of MACE in the T2DM group (adjusted HR 0.81, 95% CI 0.69-0.96). A stepwise increase of 0.1 unit in LDL-C/ApoB ratio was associated with a 5% decrease for MACE only in the T2DM group. Among participants without T2DM, there was no clear association between LDL-C/ApoB and MACE (≥1.20 vs. <1.20: adjusted HR 0.95, 95% CI 0.81-1.11; per 0.1-unit increase: adjusted HR 0.99, 95% CI 0.95-1.03). Notably, a significant interaction was observed between the LDL-C/ApoB ratio (both as a continuous and a categorical variable) and T2DM regarding the risk of MACE (P for interaction <0.05). Compared to the reference group of T2DM plus low LDL-C/ApoB level, the groups of T2DM plus high-level, non-T2DM plus low-level, and non-T2DM plus high-level LDL-C/ApoB had lower risks of MACE (adjusted HR 0.79, 95% CI 0.67-0.93; adjusted HR 0.78, 95% CI 0.67-0.91; adjusted HR 0.75, 95% CI 0.65-0.87; P for trend <0.001). No significant association was identified between MACE risk and LDL-C or ApoB in the T2DM group.

CONCLUSIONS
Our data demonstrated that in CAD patients undergoing PCI who had received statin therapy, LDL-C/ApoB ratio was related to adverse prognosis only in those with T2DM. Among patients with CAD and T2DM who are receiving statin treatment, LDL-C/ApoB may be a better indicator of residual cholesterol risk than LDL-C.