According to the latest published epidemiological data, the prevalence of type 2 diabetes in China’s urban population over 20 years of age is as high as about 10%, and according to this estimate, China’s diabetic population is close to 50 million. As we all know, the danger of diabetes is mainly due to diabetic vascular complications, and macrovascular disease is the main cause of death in diabetic patients. Some studies have shown that the incidence of cardiovascular disease is significantly higher in diabetic patients than in non-diabetic patients at the early stage of diagnosis. Patients with diabetes have a high probability of developing coronary heart disease and a high mortality rate; a high percentage of patients with coronary heart disease have combined diabetes or hyperglycemic states. In a study analyzing the correlation between coronary heart disease and diabetes risk factors, a comparison of 1059 type 2 diabetic patients with coronary heart disease and 1378 non-diabetic patients with or without a history of myocardial infarction (heart attack) found that diabetic patients without coronary heart disease had the same risk of coronary heart disease as non-diabetic patients with a previous history of coronary heart disease. Because of this, the 2001 National Cholesterol Education Program (NCEP) Adult Treatment Panel III report (ATP III) explicitly elevated diabetes without a history of coronary heart disease from a risk factor for coronary heart disease to diabetes as an equivocal risk for coronary heart disease, meaning that the risk of a new cardiovascular event (e.g., infarction or death from coronary heart disease) is the same for patients with diabetes and patients with coronary heart disease over a 10-year period. Many large epidemiological studies have shown a significant correlation between glycosylated hemoglobin (HbA1c) levels and macrovascular complications of diabetes, and this correlation already exists even when HbA1c levels are in the normal range; the higher the HbA1c level, the worse the glycemic control and the greater the risk of cardiovascular events. Therefore, aggressive glycemic control should be a key factor in the prevention and treatment of cardiovascular pathologies. However, with the disclosure of data from a series of studies, the results have been contrary to expectations. the UKPDS study published in 1998 showed that in patients with type 2 diabetes, intensive glucose-lowering therapy reduced HbA1c levels from 7.9% to 7.0%, and while patients benefited significantly from this in microvascular lesions, the effect on macrovascular endpoints did not reach a statistically significant reduction in events. Is it possible that the effective cardiovascular protection was not achieved because of inadequate glycemic control? The next series of studies aimed at reducing the risk of macrovascular complications in patients with type 2 diabetes (including the ADVANCE, ACCORD, and VADT studies) all focused on intensive glycemic control, with pre-defined HbA1c target values of less than 6.5%, 6.0%, and 6.0%, respectively, with the expectation that intensive glucose lowering would prevent the development and progression of macrovascular disease in diabetic patients by achieving the target. It is expected to prevent the occurrence and development of vascular disease in diabetic patients and reduce disability and mortality in diabetic patients through intensive glucose lowering. At the time of publication, actual HbA1c control levels were 6.5%, 6.4%, and 6.9%, respectively, all below the UKPDS control standard of 7%, but none of the intensive glycemic control showed a protective effect against cardiovascular disease; instead, the ACCORD study was terminated early because intensive glucose lowering increased patient mortality. The SUGAR trial, published in the New England Journal in 2009, showed that not only did intensive glucose lowering fail to achieve clinical benefit in a variety of critically ill patients, but survival was significantly lower in the intensive treatment group than in the conventional treatment group. These findings are puzzling as to the relationship between intensive glycemic control and the risk of cardiovascular events. The results of the UKPDS follow-up study, published in 2008, showed a significant reduction in the incidence of heart attack and all-cause death, despite the fact that patients with diabetes who initially received intensive treatment did not have intensive glycemic control over the subsequent 10 years and that HbA1c control tapered to the same level. Not coincidentally, EDIC, a follow-up study of DCCT, also showed further improvement in macrovascular disease after 10 years. These results suggest that intensive glycemic control early in the diagnosis of diabetes may result in a later benefit in terms of reduced risk of macrovascular disease, meaning that the benefit of glycemic control on macrovascular disease is not immediate, but rather the protection occurs over time, i.e., there is a “delayed effect”. A possible explanation for this is the “metabolic memory effect”. Further analysis of the ADVANCE, ACCORD and VADT studies showed that the patients enrolled were of high age, had been ill for more than 10 years, had poor glycemic control, had a high proportion of cardiovascular complications, and had a high incidence of hypoglycemia, suggesting that the patients were in the middle and late stages of diabetes. It also suggests that intensive glucose lowering should be individualized according to the person, otherwise it is counterproductive. At the same time, we are also reflecting that cardiovascular pathology is significantly higher before diabetes is diagnosed. In addition to hyperglycemia, many factors are involved in its pathogenesis, including hypertension, insulin resistance, dyslipidemia, obesity and other factors, which cause atherosclerosis through endothelial dysfunction, smooth muscle cell hyperplasia, vascular inflammation, hypercoagulable state, intimal lipid accumulation and fibrosis, and eventually cardiovascular pathology. . Hypertension, hyperglycemia, dyslipidemia, hypercoagulable state and other factors are complex and interact with each other, together with the influence of bad habits such as smoking, diet not effectively controlled, and little exercise, which makes the prevention and treatment of cardiovascular lesions cannot rely solely on blood glucose control, but requires comprehensive management, as confirmed in the Steno-2 study.The Steno-2 study intervention was mainly to observe the effect of multiple risk factors on cardiovascular disease in type 2 diabetic patients, with progressive behavioral intervention and pharmacological control of hyperglycemia, hypertension, dyslipidemia, and microproteinuria in the enrolled patients to try to reach the target values, and the use of aspirin as a level 2 prevention. At the end of the study follow-up, it was found that the risk of death was reduced by 57% and the risk of any cardiovascular event was reduced by 59% in the combined intervention group, and these data are sufficient to show that multifactorial interventions are needed for the prevention and treatment of cardiovascular pathologies. Based on the above analysis, we concluded that there is a strong relationship between intensive glycemic control and the risk of cardiovascular events, and that glycemic control has a protective cardiovascular effect. However, this protective effect has conditions and prerequisites, namely: first, the earlier the control of hyperglycemia, the better; second, individualized glucose-lowering strategies according to patients’ age and concomitant diseases; third, control of cardiovascular risk factors other than hyperglycemia, including lifestyle interventions, hypertension, dyslipidemia, hypercoagulability, etc.