Most patients with diabetes complicated with microvascular circulation disorder have normal coronary angiography but still suffer from chest tightness, chest pain and so on. Early dysfunction of coronary microcirculation is an important reason for it. It is also an important factor leading to poor prognosis of patients with diabetes. For these patients, there are still no drugs to improve microcirculation disorders. Compound Danshen dropping pills have the effects of anti-oxidation, anti-inflammatory, protecting endothelium, inhibiting the formation of atherosclerotic plaque and intimal hyperplasia, reducing oxygen consumption, improving energy metabolism, protecting cardiomyocytes, inhibiting platelet adhesion and aggregation, and improving microcirculation. However, there is a lack of clinical evidence that compound Danshen dripping pills can improve the cardiac microcirculation disturbance in diabetic patients with microangio angina. Therefore, the aim of this study was to observe the effect of Compound Danshen Dripping Pills on coronary microcirculation disturbance in diabetic patients.

Inclusion Criteria:

• Inclusion criteria: 1) age ≥ 18 and ≤ 75, male or female. 2) The microcirculation resistance index (IMR) of the left anterior descending coronary artery was ≥ 25.

  3) the diagnosis of type 2 diabetes or type 2 diabetes has been confirmed. 4) Combined with chest tightness, chest pain, palpitation, shortness of breath and other typical or atypical symptoms of angina pectoris.

  5) Coronary angiography showed no severe epicardial coronary artery stenosis (diameter stenosis rate < 50%).

  6) The patient himself agreed to participate in this study.

Exclusion Criteria:

• Subjects that meet any of the following criteria will be excluded from this study:

  1. Severe cardiac insufficiency (LVEF<40%).
  2. Atrioventricular block and bronchial asthma above II°. (3) Malignant hypertension (SBP≥200 mmHg and/or DBP≥120 mmHg) or severe hypotension (SBP < 90 mmHg).

  4) Acute myocarditis, pericardial disease, valvular heart disease, primary cardiomyopathy, myocardial infarction, severe left ventricular hypertrophy (ventricular wall or septum thickness ≥13mm).

  5) Familial hypercholesterolemia. 6) Multiple arteritis. 7) Heart stenting was performed within 3 months. 8) Coronary artery bypass grafting. 9) History of stroke within six months, history of intracranial diseases (aneurysm, arteriovenous malformation), history of extensive trauma or surgery within six weeks; 10) Active bleeding, anemia of moderate or higher severity, including known thrombocytopenia or leukopenia, severe liver or kidney dysfunction, uncontrolled infection, immune system and connective tissue diseases.

  11) those who are pregnant or lactation, or have the intention to give birth within one year, or take effective contraceptive measures during their childbearing years.

  12) Abnormal liver function (serum ALT level exceeding 3.0 times the upper limit of normal) or abnormal kidney function (eGFR≤30%).

  13) Other respiratory, digestive, blood, infectious, immune, endocrine, neuropsychiatric, tumor and other diseases of clinical significance, which may cause serious risks to patients.

  14) Patients requiring warfarin or NOAC anticoagulation treatment are taking K channel opening agents and Traditional Chinese medicine preparations for promoting blood circulation and removing stasis to improve microcirculation.

  15) Allergic to contrast agent or CDDP; 16) Life expectancy less than one year; 17) Patients who participated in other TCM clinical studies within 12 months prior to inclusion.