Diabetes has little effect on the human body if it is well controlled. However, if it is not well controlled, the long-term development will cause a series of complications, such as diabetic ketoacidosis, hyperosmolar coma, cardiovascular and cerebrovascular lesions, diabetic nephropathy, diabetic foot and so on. These complications may cause a lot of pain, discomfort and inconvenience to patients, or lead to disability or even death. Cardiovascular and cerebrovascular diseases and diabetic nephropathy renal insufficiency are the main causes of death in diabetic patients. Many poorly controlled diabetic patients may leave their lives prematurely because of these complications. Therefore, the general public should pay great attention to the dangers of diabetes. It should also be emphasized that the complications of diabetes are reversible in the early stage, and will be reversed after strict treatment, and will become irreversible once it reaches the late stage, so it is very important to have early prevention and early treatment.