Fasting blood glucose 18mmol/L is a serious excess of blood glucose, if not treated in time, it may cause acute or chronic complications, which will cause harm to the body. When the fasting blood sugar 18mmol / L, if at the same time there are “three more and one less” clinical manifestations, can be diagnosed as diabetes. For diabetic patients, this blood glucose value belongs to the control of sugar does not meet the standard. If you do not receive glucose-lowering treatment in a timely manner, it can lead to acute serious metabolic disorders, such as diabetic ketoacidosis, hyperosmolar non-ketotic diabetic coma. Long-term poor glycemic control can lead to chronic complications involving all vital organs of the body, such as diabetic nephropathy, retinopathy, diabetic foot and so on. Fasting blood glucose 18mmol / L patients should immediately go to the hospital, follow the doctor’s instructions standardized treatment.