Diastereoisomers of cyclic forms of sugars or similar molecules differing in the configuration at the C1 atom of an aldose or the C2 atom of a ketose. This atom is called the anomeric carbon. Anomers are designated α if the configuration at the anomeric carbon is the same as that at the reference asymmetric carbon in a Fischer projection. If the configuration differs the anomer is designated β. The α- and β-forms of glucose are examples of anomers (see monosaccharide).