Abstract： Objective:To investigate the effect of metformin on antiplatelet therapy after percutaneous coronary intervention (PCI) in patients with coronary atherosclerotic heart disease (CHD) and type 2 diabetes.Methods:A retrospective study was performed on 120 cases of patients with CHD combined type 2 diabetes who were admitted and underwent PCI from January 2018 to March 2019.According to whether taking metformin as metformin group ( n=45) and metformin group ( n=75), 86 cases of male, female 34 cases, aged (62.55±11.71) years old, ranging from 36 to 87 years old.The metformin group was treated with metformin in addition to conventional treatment, while the non-metformin group was treated with conventional treatment.The general situation, inhibition rate of adenosine diphosphate (ADP), platelet fibrin clot strength (MAADP) and resistance rate of clopidogrel, inhibition rate of arachidonic acid and resistance rate of aspirin in the two groups were analyzed. Results:There were no statistically significant differences in body mass index, fasting blood glucose, hemoglobin a1c, platelet count, total cholesterol, triglyceride and uric acid between the two groups ( P>0.05). The inhibition rate of ADP[(46.18±21.75) %]in the metformin group was higher than that in the non-metformin group[(37.68±11.90) %], the resistance rate of MAADP[(35.91±10.98) mm]and clopidogrel[24.4% (11/45)]was lower than that in the non-metformin group[(44.35±11.71) mm and 42.7% (32/75)], with statistically significant differences ( P<0.05). The inhibition rate of arachidonic acid in the metformin group[(66.86±21.09) %], the resistance rate of aspirin[17.8% (8/45)]and the non-metformin group[(69.91±23.25) %, 22.7% (17/75)]showed no significant difference ( P>0.05). Conclusion:Metformin can improve the sensitivity of antiplatelet drugs in patients with coronary heart disease complicated with T2DM after PCI, and a certain dose of metformin orally according to the condition may improve the long-term prognosis of patients.