Diabetes mellitus is a common clinical metabolic disease characterized by elevated blood glucose. Its pathogenesis is complex, and the etiology and treatment vary between different subtypes. The current common is the typing criteria proposed by WHO Diabetes Expert Committee in 1999. The so-called type 2 diabetes is relative to type 1 and other types of diabetes. Type 1 diabetes: The main cause is the destruction of pancreatic beta cells and absolute deficiency of insulin secretion, which is more common in congenital form. Type 2 diabetes: its etiology is quite complex. There are genetic factors, similar to type 1 diabetes, and type 2 diabetes is characterized by a family history. Secondly, there is also a relationship with obesity, especially in central obese patients whose excess fat is concentrated in the abdomen, which is more likely to develop type 2 diabetes than those whose fat is concentrated in the buttocks and thighs. Thirdly, there is also a relationship with age, especially for people over 55 years of age and above, who are obese and overweight related to insufficient exercise. Fourthly, it is related to the change of individual’s lifestyle, high calorie and inactivity are the triggering factors of diabetes. This leads to a progressive process of insulin resistance with progressive insulin insufficiency, to progressive insulin insufficiency or insulin resistance, mostly with a gradual onset in later life. Other specific types of diabetes mellitus: It is a type of hyperglycemic state with relatively clear etiology at different levels other than type 1 and type 2, such as genetic defects in pancreatic β-cell function, genetic defects in insulin action, exocrine diseases of the pancreas, other endocrine diseases, diabetes mellitus caused by drugs or chemicals, infections, uncommon immune-mediated diabetes mellitus, other genetic syndromes related to diabetes mellitus, etc. These These factors or diseases can eventually lead to abnormal blood glucose and meet the criteria for the diagnosis of diabetes mellitus. Gestational diabetes: refers to varying degrees of abnormal glucose metabolism occurring during pregnancy, but does not include patients with diabetes already diagnosed before pregnancy, which is referred to as a combined diabetic pregnancy. Therefore, the so-called type 2 diabetes is a type characterized by insulin resistance compared to other types, but with the advancement of medical technology, diabetes is no longer limited to the classification of type 1 and type 2, and the treatment has been varied and diversified.