In a clinical survey, it was shown that the coexistence of diabetes and coronary artery disease is very common. However, many of them have never had chest pain and therefore know very little about their condition and cannot talk about systematic treatment anymore, while some patients with coronary heart disease are detected by electrocardiography or ambulatory ECG monitoring. Most people recognize that coronary heart disease and stroke are the main causes of disability and crippling death in diabetic patients. Summary statistics from several large hospitals in China show that up to about 50% of deaths from diabetes are due to cardiovascular complications. Others have observed that the incidence of diabetes combined with coronary heart disease is two to four times higher in non-diabetics. All of these findings indicate that there is an inextricable relationship between diabetes and coronary heart disease. The clinical manifestation of diabetes combined with coronary heart disease is very insidious, and the typical chest pain (angina pectoris) is rarely seen, which often leads patients to neglect the diagnosis and treatment of coronary heart disease, but it can become a hidden danger of sudden death. So, why does diabetes combined with coronary artery disease often not cause chest pain? Some people have concluded after analyzing a large number of cases that: (1) Diabetes is prone to cause vegetative neuropathy. Long-term hyperglycemia can reduce the number of nerve fibers by 20% to 40%, thus weakening or interrupting the transmission of pain impulses; (2) In a long period of hyperglycemia, the patient’s body will produce more endorphins, leading to an increase in the patient’s cardiac nociceptive threshold and a decrease in sensitivity to pain. As a result, angina attacks are often missing clinically, as is customary in patients with coronary artery disease. However, this phenomenon does not mean that the lesions are not serious, but on the contrary, the pathology shows that the coronary artery lesions caused by diabetes mellitus involve a wide range of vessels, which often makes interventional treatment or “bypass” surgery difficult. Because of its clinical features (as described above), it is even more dangerous and deceptive. How to detect coronary artery disease in diabetes early? Diabetes and cardiovascular disease experts jointly advocate that even if a diabetic patient does not have chest pain, he or she should have a routine ECG or, if necessary, an ambulatory ECG test every six months or a year.