Diabetes mellitus is a common and multi-infection disease, and its prevalence is rapidly increasing with the improvement of people’s living standards, aging population and lifestyle changes, and it has now become the third largest non-communicable disease in the world. At the World Congress on Diabetes Prevention and Research held in Geneva in 1992, the issue of active tertiary prevention of diabetes was raised and a unified understanding was reached. Primary prevention: primary prevention is to avoid the onset of diabetes. The main work of primary prevention includes three aspects: first, to promote knowledge about diabetes; second, to promote healthy behaviors, such as reasonable diet, moderate exercise, avoiding obesity, quitting smoking and limiting alcohol, and psychological balance; third, regular checkups, once impaired glucose tolerance (IGT) or impaired fasting glucose (IFG) is detected, early intervention should be implemented. Interventions for primary prevention include lifestyle intervention and drug intervention. Clinical trials have demonstrated that the risk of diabetes can be reduced through a series of lifestyle interventions such as weight loss, increased physical activity, and dietary modification. Second, the application of pharmacological interventions such as metformin and acarbose can also play a role in reducing the occurrence of diabetes. Secondary prevention: Secondary prevention is the early detection and effective treatment of diabetes mellitus. Blood glucose measurement should be included in routine physical examinations, and even in those who are normal, it should still be measured regularly. If there are abnormal symptoms such as excessive drinking, excessive eating, excessive urination, weight loss, itchy skin, etc., they must be carefully examined and diagnosed early. In terms of treatment, the four principles of early treatment, long-term treatment, comprehensive treatment and individualization of treatment measures should be implemented. The International Diabetes Federation (IDF) has put forward five points of modern treatment for diabetes blood glucose control: (1) Dietary treatment. Control the total caloric intake of food per day, and the daily diet should be low in fat, moderate in protein and high in carbohydrate. Advocate high-fiber diet, light diet, adhere to a small number of meals, regular and fixed meals; (2) appropriate exercise. Physical exercise should be done after meals, and the duration should not be long and the intensity should not be large; (3) medication, including oral medication and insulin; (4) blood glucose monitoring. Patients need to master self-monitoring techniques, learn how to monitor blood glucose and the frequency of monitoring; (5) diabetes education. In addition, diabetes treatment should be comprehensive to meet the standard, in addition to satisfactory blood glucose control, it also requires normal or near normal blood lipid and blood pressure, maintaining weight in normal range, and having good mental status. Tertiary prevention: Tertiary prevention is the delay and/or prevention of diabetic complications. Patients with diabetes need to be better educated about diabetic complications, such as the types, dangers, severity of complications and their risk factors, and preventive measures. Screening for complications should be performed as early as possible for early detection and management. The development of chronic complications may be terminated or reversed at an early stage through effective treatment, and both the DCCT and UKPDS trials have demonstrated that strict control of blood glucose and blood pressure can reduce mortality and disability rates in patients with diabetes. Therefore, it is necessary to actively control blood glucose to basic normal at an early stage, and to carefully control such unfavorable factors as obesity, hypertension, disorders of lipid metabolism, smoking and heavy alcohol consumption, pay attention to the combination of work and rest, reasonable diet, appropriate physical activity and proper medication.