Compositions, devices, kits and methods are disclosed for assaying glucose with a glycosylated, modified flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH), variant thereof or an active fragment thereof, where at least one asparagine residue at positions N2, N168 and N346 of mature, wild-type A. oryzae FAD-GDH according to SEQ ID NO:2 is substituted by one or more amino acids not suitable for glycosylation, thereby eliminating or inactivating, respectively, a potential glycosylation site at this position.