Abstract Background Elevated remnant cholesterol (RC) is considered a risk factor for ischemic events in patients with coronary artery disease (CAD). Recently evidence demonstrates a close connection between RC and cardiometabolic disorders, particularly diabetes mellitus (DM). However, it remains unclear whether different glucose metabolism statuses modify the association between RC and ischemic risk after percutaneous coronary intervention (PCI). Purpose This study aims to explore whether glucose metabolism statuses alter the relationship between RC and ischemic risk in CAD patients undergoing PCI. Methods This prospective study enrolled consecutive 10,724 CAD patients undergoing PCI throughout 2013. Patients were categorized into three groups: DM, pre-DM, and normal glucose regulation (NGR) group. Fasting RC was calculated as total cholesterol minus low-density lipoprotein cholesterol and high-density lipoprotein cholesterol, and was analyzed based on tertile levels (low, middle, and high). The clinical endpoint was major adverse cardiovascular and cerebrovascular events (MACCE, including cardiac mortality, revascularization and stroke). Results A total of 9,406 PCI patients were ultimately included, among whom the average age was 58.44 ± 10.26 years and 2,142 (22.80%) were female. During 5-year follow-up, 1,876 (19.9%) patients experienced MACCE. In the overall cohort, the highest RC tertile was associated with a higher risk of MACCE (hazard ratio [HR]: 1.129, 95% confidence interval [CI]: 1.006-1.267) compared to those in the lowest tertile (Figure 1). Importantly, a significant interaction was observed between RC levels and glucose metabolism statuses (P for interaction = 0.032). In the DM group, multivariate Cox regression analysis revealed that the highest tertile of RC significantly increased a 1.172-fold risk of MACCE (HR:1.172, 95% CI:1.004-1.369). However, neither the pre-DM nor NGR groups showed any significant association between RC and MACCE (both P > 0.05). Further subgroup analysis found that the correlation between the highest tertile of RC and an increased MACCE risk was only in the DM group, which was prominent among females (Figure 2). Conclusions In a large-scale 5-year follow-up study, we are the first to demonstrate that RC-related ischemic risk may be exacerbated by diabetes in CAD patients undergoing PCI, highlighting the potential benefits of intensifying RC-lowering treatments for PCI patients combined with DM.