Cyclization of the open chain structure of D−(+) - glucose has created a new stereocenter at C1 which explains the existance of two cyclic forms of D - (+) - glucose, namely α− and β− . These two cyclic forms are diasteromers, such diasteromers which differ only in the configuration of chiral carbon developed on hemiacetal formation (it is C1 in glucose and C2 in fructose) are called anomers and the hemiacetal carbon (C1. or C2) is called the anomeric carbon.