A fasting blood sugar of 13 mmol/L is not necessarily considered severe diabetes. A single episode of markedly elevated fasting blood glucose without any symptoms is usually not diagnostic of diabetes. On the other hand, a diagnosis of diabetes can be considered if typical diabetic symptoms are present, at which point the blood glucose value is well above the normal range, which is usually more serious, and prompt medical attention is recommended. Whether diabetes is serious or not is not only related to a particular fasting blood glucose, but also related to the overall blood glucose and the presence of complications, which should be evaluated in a comprehensive manner. If a diabetic patient has a fasting blood glucose of 13mmol/L or more, accompanied by complications, such as blurred vision, a foreign body sensation in front of the eyes and other changes of diabetic retinopathy, or numbness and pain in both lower limbs and other manifestations of diabetic retinal neuropathy, then we consider that diabetes may be a more serious condition. Fasting blood glucose 13mmol / L should be timely to the hospital for a full evaluation of the consultation.