Hyperosmolar nonketotic diabetic coma is a common acute complication of diabetes mellitus with a higher mortality rate than diabetic ketoacidosis and requires active treatment. The characteristics of hyperosmolar nonketotic diabetic coma include the following: i. It occurs mostly in elderly patients without a history of diabetes mellitus. Second, neurological manifestations are dominant, which can be manifested as irritability, delirium, drowsiness or even lethargy, coma and other neurological manifestations, and there can be focal loss of limb muscle strength, etc., mostly caused by high blood glucose level breaking through the regulatory mechanism of cerebrovascular. Third, blood glucose elevation is obvious, more than 27.8 mmol/L, or even more than 33.3 mmol/L, and blood osmolality is obviously elevated. Fourth, there can be mild elevation of urinary ketone body and blood ketone body, but not combined with diabetic ketoacidosis.