The purpose of the study was to assess whether the occurrence of restenosis is associated with CD45+ platelet count and neutrophil to lymphocyte ratio in patients with type 2 diabetes mellitus (DM) after drug-eluting stent (DES) implantation for stable coronary artery disease (CAD). The study comprised 126 patients, including 55 patients with type 2 DM and stable CAD who underwent elective coronary artery stenting with DES and follow-up angiography within 6 to 12 months. Blood samples were collected from each patient on the morning of the coronary angiography procedure. The variables related to in-stent restenosis were selected by logistic regression analysis. The logistic regression analysis showed that 2 inflammatory factors, CD45+ platelet count (odds ratio [OR] = 4.51, 95% confidence interval [CI]: 1.50-13.50, P = .007) and neutrophil to lymphocyte ratio (OR = 3.09, 95% CI: 1.05-9.10, P = .04), were significantly associated with the risk of in-stent restenosis after stenting with DES in patients with stable CAD and type 2 DM. A receiver operator characteristic curve analysis indicated that the area under the curve was 0.83% (0.05%; P < .001), which showed that the logistic model had good predictive accuracy (based on CD45+ platelet count and neutrophil to lymphocyte ratio) for the risk of in-stent restenosis development in DES in patients with CAD and type 2 DM. Two novel biomarkers of restenosis, CD45+ platelet count and neutrophil to lymphocyte ratio, may be effectively used to predict in-stent restenosis after DES implantation in patients with CAD and type 2 DM.