We discovered that glucose directly bind to DDX21, induced the conformation change of the proteins and inhibit its helicase activity. Glucose also inhibits the dimerization of DDX21, re-localize DDX21 from nucleolus to nucleoplasm and reassemble DDX21 to RNA splicing complex. DDX21 is essential for epidermal differentiation while with normal glucose condition, DDX21 was re-localized from nucleolus to nucleoplasm, bind to splicing factors and mRNA introns more to regulate splicing of key differentiation factors and promote epidermal differentiation.