D-glucose is a short form of dextrorotatory glucose. It is one of the two stereoisomers of glucose, and is the one that is biologically active. It occurs in plants as a product of photosynthesis. In animals and fungi, it is the result of the breakdown of glycogen. In humans, it is present in blood and urine in which the normal clinical values are 75-115 mg/dl for blood, and 50-300 mg/24 hr for urine.