After the blood sugar exceeds 30mmol/l, the main dangers include ketoacidosis and hyperosmolar coma. 1. Ketoacidosis: mainly belongs to the blood sugar obviously rises, itself for the glucose metabolism ability obviously decreases, further leads to the body fat decomposition, will form a large number of ketone bodies into the bloodstream, a long time poorly controlled will lead to ketoacidosis, the serious cause of the patient’s coma. 2. Hyperosmolar coma: a neurological symptom caused by poor glycemic control, mainly due to a significant increase in plasma osmolality, which further leads to cellular water loss, causing significant neurological dysfunction and coma symptoms. A significant increase in blood glucose, accompanied by abnormalities in the function of the nervous system, the need for timely medical observation, diagnosis of the condition under the guidance of the doctor to carry out standardized treatment, to avoid causing delays in the condition.