Fasting blood glucose of more than 30 mmol/L indicates a severe elevation of blood glucose, which may lead to acute complications such as diabetic ketoacidosis and diabetic non-ketotic hyperosmolar syndrome, and prompt medical attention is recommended. The normal range of fasting blood glucose for normal people is 3.9~6.1mmol/L. Fasting blood glucose of more than 30mmol/L has exceeded the upper limit of the normal range by 5 times, which may cause a series of serious acute complications. Such as diabetic ketoacidosis, diabetic hyperosmolar hyperglycemia syndrome, etc., causing patients dehydration, acid-base imbalance, shock, coma and other serious consequences, and may even be life-threatening. Fasting blood glucose more than 30 mmol/L, especially when the above complications occur, should promptly seek medical attention, under the guidance of a professional physician timely use of adequate amount of insulin, correction of acid-base balance, active rehydration and other symptomatic supportive treatment, to avoid further development of the condition.