Diabetes is a chronic disease, and poorly controlled blood glucose diabetes can be complicated by a variety of acute and chronic complications that cause multisystem symptoms. The following diseases should be considered as causes of coma in diabetic patients: i. Acute complications of diabetes caused by hyperglycemia. With short-term hyperglycemia, acute complications such as ketoacidosis coma, hyperosmolar coma or lactic acidosis coma can occur in diabetic patients. Second, hypoglycemic coma caused by low blood sugar, diabetic patients who are receiving oral hypoglycemic drugs or insulin therapy may experience hypoglycemia when the diet is irregular or meals are not timely, and serious hypoglycemic coma may occur. Third, combined with cardiovascular disease, diabetic patients are prone to cerebral artery, coronary artery atherosclerosis, and even cerebral infarction, myocardial infarction, angina pectoris, heart failure, etc. When combined with serious cardiovascular disease, diabetic patients can be manifested as coma. Fourth, the combination of diabetic nephropathy, uremia can occur when the uremic coma. Fifth, serious infections can also cause infectious toxic shock, which can also lead to coma.