Fasting blood glucose of 18 mmol/L is usually not the only way to determine how long a patient has had the disease. The onset of fulminant type 1 diabetes is more rapid and the duration of the disease is generally shorter; type 2 diabetes has an insidious onset, and when a patient is found to have a blood glucose of 18 mmol/L, it means that the duration of the disease is likely to be longer. A fasting blood sugar of 18 mmol/L is usually seen in patients with diabetes. Burst type 1 diabetes mellitus belongs to a new subtype of type 1 diabetes mellitus, the onset of the disease is rapid, can quickly appear fasting blood glucose increase, before the onset of the disease can have symptoms of antecedent infections, so this disease appears fasting blood glucose 18mmol / L may be a shorter course of the disease. Type 2 diabetes mellitus patients with insidious onset of disease, due to patients may not have obvious clinical manifestations, it is more difficult to find diabetes, so type 2 diabetes mellitus patients with fasting blood glucose 18mmol / L indicates that the course of the disease may be longer. It is recommended to go to the hospital and ask the doctor to make a judgment when fasting blood sugar 18mmol/L occurs.