Diabetes mellitus is a relatively common endocrine metabolic disease. It is mainly caused by insufficient secretion of insulin and inappropriate overproduction of pancreatic hyperglycemia. It is mostly seen in patients over 40 years old who have a sweet tooth and are obese, more in urban than rural areas, and often has a family history, so it is related to genetics. In a few patients, it is related to viral infection and autoimmune reaction. The main symptoms are irritability, excessive drinking, polyuria, polyphagia, fatigue and wasting. The common disease of life, accompanied by hypertension, coronary heart disease and hyperlipidemia, is life-threatening in severe cases. Diabetes belongs to a lifelong metabolic disease, under the current medical technology can not completely cure diabetes, only through various ways to control blood sugar, if the blood sugar control is not good is likely to cause diabetes complications appear, then what are the complications of diabetes? First, the complications of diabetes are divided into two kinds of acute and chronic. 1, acute complications include: diabetic ketoacidosis, hyperosmolar non-ketotic diabetic coma, lactic acidosis, etc.. Elderly diabetic patients are prone to hyperosmolar non-ketotic diabetic coma, often induced by infection and stress, characterized by extraordinarily high blood glucose without obvious diabetic ketoacidosis, manifested by hyperglycemic state, dehydration and progressive impairment of consciousness. The disease is severe and the prognosis is poor. Chronic complications include: (1) macrovascular complications: including cardiovascular, cerebrovascular and peripheral vascular lesions, and coronary artery disease, stroke and lower limb gangrene. (2) Microvascular complications: usually refers to diabetic retinopathy and diabetic nephropathy. Diabetic retinopathy is a common cause of blindness. Diabetic nephropathy is a serious microvascular complication and is one of the leading causes of death in diabetic patients. (3) Neuropathy: Peripheral neuropathy is one of the more common chronic complications of diabetes mellitus. It manifests as symmetrical numbness, pins and needles, burning sensation, and pain in the hands and feet. (4) Diabetic foot: It is the most serious complication of diabetes mellitus. It is characterized by pain in the foot, skin breakdown and ulceration of the foot, and the lesions are mostly progressive and can lead to amputation in severe cases. Therefore, diabetic patients should always pay attention to the changes in the foot and seek medical treatment in time when abnormalities are detected. Second, diabetic patients how to effectively prevent the occurrence of complications of diabetes? 1, quit smoking. 2.To do every day: check both feet for wounds, blisters, erythema and swelling. Contact your doctor immediately for any pain that will not go away; brush your teeth every day to avoid mouth, teeth and gum problems; monitor your blood sugar according to your doctor’s recommendations. 3. At each visit, you must have: a blood pressure check; a foot check; and a physical examination. 4.Two glycated hemoglobin (HbA1c) tests per year. 5. Once a year: cholesterol test; triglyceride test; comprehensive foot exam; teeth and gum exam to tell your dentist you have diabetes; dilated pupil exam to check for eye disease; urine and blood tests to check for kidney problems. Nowadays, there is no one cure for diabetes, but using the right methods can provide relief and eliminate other complications, as well as allow the patient to achieve a higher standard of quality of life. As a diabetic patient, not only should you pay attention to the details of life, regular checkups are also necessary, and if you take medication, you must take it according to the actual situation and not exceed the limit.