The danger of diabetes is very high for both society and patients, and it is not yet curable. The number of people with diabetes in China is the highest in the world, and it places a huge economic and social burden on the government and society. Diabetes itself may only be manifested as high blood sugar, early on there may be no symptoms or slight three more or less. However, its harm is mainly reflected in a variety of acute and chronic complications, especially chronic complications, whose risk of disability and death is very high. The most common of them include diabetic nephropathy, diabetic retinopathy, diabetic foot and so on. Due to kidney damage, patients often develop severe hypertension, edema, followed by a series of symptoms of renal insufficiency. Due to the eye damage, patients may experience loss of vision, bleeding from the fundus of the eye or even blindness. Most of the kidney and eye diseases are irreversible changes, and the changes can put a serious burden on the patient due to their simultaneous existence. And diabetic foot is currently the most common cause of foot amputation, and the survival rate of patients will be significantly reduced after the occurrence of podiatry and amputation. In conclusion, the dangers of diabetes are diverse and enormous, and one should control blood glucose as well as possible, do a good job of comprehensive management, and reduce the occurrence of complications.