Glucose. Computer graphic of a molecule of the glucopyranose form of D-glucose, also known as dextrose or grape sugar, the principal fuel that cells use to power themselves. D-glucose is comprised of atoms of carbon (C, blue), hydrogen (H, white) and oxygen (O, red), and has the chemical formula C6H12O6. It can have many forms, the glucopyranose type featuring a ring of 5 carbons and 1 oxygen. Glucose is found in many plants and is a normal component of blood. It is a constituent of starch, cellulose, glycogen, sucrose and many glycosides from all of which it can be obtained by hydrolysis with acids or enzymes.