the sugar in the blood is called blood sugar, and in most cases it is glucose. most of the energy required for the activities of various tissue cells in the body comes from glucose, so blood sugar must be maintained at a certain level to maintain the needs of various organs and tissues in the body. normal people's fasting blood glucose concentration in the morning is 80 to 120 mg%. a fasting blood glucose concentration exceeding 130 mg% is called hyperglycemia. if the blood sugar concentration exceeds 160 to 180 mg%, part of the glucose will be excreted in the urine, which is glycosuria. a blood sugar concentration below 70 mg% is called hypoglycemia.