Diabetes mellitus is a group of diseases characterized by chronic hyperglycemia. The etiology of different types of diabetes mellitus varies and so does the prognosis. Type 1 diabetes: The main cause is abnormal function or apoptosis of pancreatic β-cells due to genetic factors or autoimmune defects, and absolute deficiency of insulin secretion. In addition, environmental factors such as viral infection and stimulation by harmful substances can also cause the destruction of beta cells. This type of diabetes is generally incurable and can only be treated with insulin for life. Type 2 diabetes: Defective pancreatic β-cell function caused by insulin resistance and acquired factors, which are both congenital and acquired, such as obesity and metabolic syndrome. type 2 diabetes is likely to stop or progress slowly with timely treatment early in the onset of the disease and removal of risk factors, but also requires lifelong medication. Gestational diabetes: This category is generally due to changes in basal metabolism and hormone levels during pregnancy, resulting in disorders of glucose metabolism that may either first appear during pregnancy or be triggered by previous high-risk factors. It may be related to the effects of HCG (chorionic gonadotropin) and estrogen on glucose metabolism. Most patients with gestational diabetes are treated and their blood glucose returns to normal after delivery, but some patients develop lifelong diabetes. Other types: With the progress of medical technology, some special types of diabetes mellitus have been found clinically, with characteristics of both type 1 and type 2, such as autoimmune diabetes mellitus, and some diabetes mellitus caused by special etiologies such as abnormal insulin-producing secretion, abnormal islet alpha cell function, abnormal intestinal flora, etc. However, the specific pathogenesis is under study and inconclusive, and the prognosis of these types of diabetes mellitus depends on the primary etiology The prognosis of these types of diabetes depends on the primary cause, and if the primary cause can be eradicated, its resulting hyperglycemia may also be cured, but if the cause is unknown or the cause cannot be eradicated, it is generally difficult to cure. Therefore, the etiology and pathogenesis of diabetes are extremely complex, treatment is highly individual, and the prognosis is not generalized. In general, traditional type 1 and type 2 diabetes are basically treated for life.