The Chinese Guidelines for the Prevention and Treatment of Type 2 Diabetes were published in 2003 and the first revision was made in 2007. Clinical and basic research on type 2 diabetes at home and abroad has made great progress in the past three years, with successes and failures, and some studies have even overturned the original understanding and concepts. Whether successes or failures, they have had a great impact on the diagnosis and treatment of type 2 diabetes, and have the same effect on the prevention and treatment of diabetes in China. Therefore it is very necessary to revise the guidelines for the prevention and treatment of type 2 diabetes in China. At the same time, considering the specific situation of diabetes prevention and treatment in China, the Chinese Diabetes Society has formulated the principles for the future revision of the guidelines for the prevention and treatment of type 2 diabetes in China: the guidelines will be revised from time to time according to the latest research progress at home and abroad, generally every 2 to 3 years, gradually transitioning to once a year, and published in the Chinese Journal of Diabetes or issued in a single volume, as well as on the Chinese Medical Association Diabetes Society (CDS) website. In order for readers to better understand the main content and basis of this revision, the following description is provided. I. Prevalence of diabetes in China From 2007 to 2008, an epidemiological survey on diabetes was conducted in 14 provinces and cities nationwide, organized by the CDS. Through weighted analysis, after taking into account gender, age, urban-rural distribution and regional differences, it was estimated that the prevalence of diabetes in adults over 20 years of age in China was 9.7%, and the total number of adults with diabetes reached 92.4 million. China may have become the country with the largest number of people with diabetes. II. Diagnostic criteria for diabetes mellitus in China This guideline still adopts the criteria of the World Health Organization (WHO) in 1999. HbA1c has been widely used as the gold standard for reflecting average blood glucose and evaluating glycemic control. In 2010, the American Diabetes Association (ADA) has adopted HbA1c≥6.5% as the primary diagnostic criterion for diabetes, and recently the WHO has also recommended the adoption of HbA1c as a diagnostic tool for diabetes where conditions are ripe, and recommended HbA1c>6.5% as the as the cut-off point for the diagnosis of diabetes. However, due to the relative lack of information related to the HbA1c diagnostic cut point for diabetes in China, especially the lack of standardization of HbA1c measurement in China, this includes the obvious regional differences in the quality control of measurement instruments and measurement methods. Therefore, it is too early to apply HbA1c to diagnose diabetes in China, which may lead to confusion in the diagnosis of diabetes. The main basis for setting the control standard of HbA1c as <7% is: (1) It is consistent with the major international diabetes guidelines. (2) Several large evidence-based medical studies (e.g. UKPDS, DCCT, Kumamoto, etc.) have demonstrated that microvascular complications of diabetes have been significantly reduced when HbA1c is reduced to 7%, and further reduction of HbA1c, although it may be beneficial for microvascular lesions, increases the risk of hypoglycemia. (3) Several recently completed clinical trials have observed that in patients with type 2 diabetes who have a longer duration of diabetes, carry more risk factors for macroangiopathy or have developed macroangiopathy, more intensive glycemic control (HbA1c <7%) may not reduce the risk of macroangiopathy and death, but may be associated with an increased risk of death. However, the need for individualization of diabetes treatment is also emphasized. The guidelines particularly emphasize that in the early stages of diabetes, patients with relatively good pancreatic islet function, no serious complications, use of drugs that do not significantly cause hypoglycemia, and those with easily controlled blood glucose should lower their blood glucose to normal as much as possible, i.e., HbA1c < 6%. IV. Management of cardiovascular risk factors and comprehensive treatment Cardiovascular disease is the main cause of disability and death in type 2 diabetes. A large body of evidence-based medical evidence shows that comprehensive treatment (standard therapy) including lifestyle interventions, hypoglycemia, hypotension, lipid regulation and antiplatelet therapy is the most effective measure to significantly reduce the risk of major and minor vascular complications and death in diabetes. This guideline emphasizes the importance of comprehensive treatment and provides a roadmap for screening and clinical treatment decisions for the clinical application of standard of care measures. The NICE-SUGAR study published in the New England Journal is the largest, population-wide prospective clinical trial to date. The study found that stricter control of blood glucose in critically ill patients increased the risk of death in critically ill patients compared to the conventional glucose-lowering group. Therefore, the current international recommendation for glycemic control requirements for critically ill patients is 7.8 to 10.0 mmol/L. VI. Selection and treatment process of glucose-lowering drugs The guidelines provide a general description of all types of glucose-lowering drugs that have been marketed in China, and all of them are included in the appendix. Drug effectiveness, safety and health economics factors are still important factors in selecting therapeutic drugs. Drugs that have been on the market for a long time and have been proven to have good efficacy and safety by large clinical trials and other evidence-based medicine are placed in a priority position. Although thiazolidinediones (TZDs) have good hypoglycemic effects, clear side effects have been observed in recent years, such as edema, induction or exacerbation of heart failure, and fractures. Therefore, the observation of the safety of newly marketed drugs must be strengthened to ensure the best interests of diabetic patients. Regarding the process of diabetes treatment, the prevalence of type 2 diabetes in China has increased significantly in recent years, and the proportion of obese or overweight people has increased. Some studies have proved that metformin also has good efficacy in people with normal weight. Therefore, metformin is preferred on the basis of lifestyle interventions, and further measures will be taken if the target cannot be achieved. It is also taken into account that some patients experience wasting and have gastrointestinal reactions after taking the drug, which are not suitable for metformin and can choose other drugs. Seven, the choice of insulin initiation therapy When oral hypoglycemic drugs cannot effectively control blood sugar, additional insulin therapy is required. For the choice of insulin preparations, a lot of research has been conducted in recent years, mainly on whether to choose basal insulin or premixed insulin. The advantages of choosing basal insulin are simplicity, good patient compliance, better control of fasting glucose, and relatively less hypoglycemia. Premixed insulins, including premixed insulin analogs, can be chosen as a once-daily or twice daily injection regimen. The once-daily regimen is also a more convenient option for starting treatment. The efficacy of 2 injections per day is better than that of 1 injection, but the incidence of hypoglycemia is relatively high. Intensive therapy (3 to 4 insulin injections per day or insulin pump) is still the last choice. Therefore, correct analysis of patient characteristics and familiarity with the characteristics of various insulins are necessary for the implementation of insulin therapy. Surgical treatment of diabetes mellitus Surgical treatment of obese patients with type 2 diabetes mellitus has good efficacy, and the short-term efficacy even exceeds that of various drugs. At present, the surgical treatment of obesity with type 2 diabetes has been recognized by IDF and ADA as one of the means of treating diabetes. In China, this treatment has also been carried out and a consensus has been formed in the diabetes and surgical community. The main purpose of adding this chapter is to standardize the indications for surgery and the management of patients before and after surgery, weighing the pros and cons, avoiding the expansion of surgery and reducing the risk of long- and short-term complications of surgery. Anti-platelet therapy The main changes are in primary prevention, for diabetic patients with 10-year cardiovascular risk >10%, routine application of low-dose aspirin; for patients with 10-year cardiovascular risk of 5%-10%, consider the application of low-dose aspirin; for patients with 10-year cardiovascular risk of <5%, do not use low-dose aspirin. X. Lower extremity vascular lesions The screening pathway, diagnostic criteria and multiple treatment methods for lower extremity vascular lesions are proposed. In order to save the ischemic limb, endovascular minimally invasive treatment and surgical treatment can be chosen. The revision of this edition of the guideline is mainly based on the 2007 version. In the process of revision, more attention was paid to reflect the latest evidence of domestic and foreign medicine, and the opinions of domestic experts in the endocrine community and related fields were widely consulted to make the guideline more representative and authoritative.