Objective. To investigate the effect of dapagliflozin therapy on the clinical outcome of drug-eluting stent (DES) implantation in elderly patients with type 2 diabetes mellitus (T2DM). Methods. We retrospectively studied the real-world data of patients with coronary heart disease who received DES implantation in our hospital from May 2019 to May 2021. Baseline general data and laboratory results of patients were collected. All patients were followed up for two years after PCI, and the follow-up endpoints included in-stent restenosis, major adverse cardiovascular events (MACE), revascularization, rehospitalization, and all-cause mortality. Results. Compared with those before treatment, body mass index, systolic blood pressure, diastolic blood pressure, TG, TC, LDL-C, FBG, and HbA1c were decreased in both groups after treatment, while HDL-C was increased after treatment (
P
<
0.05
). There were significant differences in BMI, systolic blood pressure, diastolic blood pressure, FBG, and HbA1c between the two groups before and after treatment. At the end of follow-up, the incidence of in-stent restenosis and MACE in the dapagliflozin group was lower than that in the nondapagliflozin group. K-M curve analysis showed a significant difference in in-stent restenosis and MACE after DES implantation between the dapagliflozin group and the nondapagliflozin group (
logrank
χ
2
=
5.093
, 4.524;
P
=
0.024
, 0.033). Conclusion. In accurate clinical data, dapagliflozin could significantly improve the postoperative BMI, blood pressure, and blood glucose outcome of patients with T2DM complicated with coronary heart disease and positively impact in-stent restenosis and MACE.