Abstract： Background::Preliminary studies have indicated that Shexiang Baoxin Pill (MUSKARDIA) has a coronary artery dilation effect and increases the coronary blood flow, relieving the symptoms of angina. This study aimed to evaluate the benefit of MUSKARDIA on patients with stable coronary artery disease (CAD) and diabetes mellitus (DM).Methods::This was a subgroup analysis of a multicenter, randomized, placebo-controlled phase IV trial. CAD patients with a medical history of DM or baseline fasting blood glucose (FBG) ≥7.0 mmol/L were grouped according to the treatment (standard therapy plus MUSKARDIA or placebo). The primary outcome was major adverse cardiovascular events (MACEs), which was the composite outcome of cardiovascular death, non-fatal myocardial infarction, and non-fatal stroke. The secondary outcome was the composite outcome of all-cause death, non-fatal myocardial infarction, non-fatal stroke, hospitalization for unstable angina or heart failure, and coronary angioplasty.Results::MACEs occurred in 2.6% (9/340) and 4.8% (18/376) of patients in the MUSKARDIA and placebo groups, respectively ( P = 0.192). Secondary composite outcome was significantly less frequent with MUSKARDIA than with placebo (15.3% [52/340] vs. 22.6% [85/376], P = 0.017). Risk of MACEs (hazard ratio [HR] = 0.69, 95% confidence interval [CI]: 0.31-1.57) was comparable between two groups. In patients with uncontrolled DM (≥4 measurements of FBG ≥7 mmol/L in five times of follow-up), the risk of secondary outcome was significantly lower with MUSKARDIA (5/83, 6.0%) than with placebo (15/91, 16.5%) (HR= 0.35, 95%CI: 0.13-0.95). Conclusion::As an add-on to standard therapy, MUSKARDIA shows a trend of reduced MACEs in patients with stable CAD and DM. Furthermore, MUSKARDIA may reduce the frequency of all-cause death, hospitalization, and coronary angioplasty in this population, especially in those with uncontrolled DM.Trial Registration::ChiCTR.org.cn, ChiCTR-TRC-12003513