A method for measurement of hemoglobin Alc in a sample comprising contacting an HbAlc dehydrogenase capable of directly acting on hemoglobin Alc with hemoglobin Alc in a sample in the presence of an electron mediator that is not oxygen and measuring a reduced electron mediator that is not hydrogen peroxide generated by the action or an oxidized electron mediator that is not oxygen consumed by the action, wherein a protease is not applied to the sample, wherein the measurement is based on measuring the dehydrogenase activity of the HbAlc dehydrogenase, wherein the HbAlc dehydrogenase comprises an amino acid sequence having 90% or higher sequence identity with the amino acid sequence as shown in SEQ ID NO: 14 over the full length and comprises an amino acid substitution at one or more amino acid positions corresponding to positions 62, 63, 64, 68, 99, 102, 106, 110, 113, 355, 356 and 419 of the amino acid sequence of SEQ ID NO:1, and comprises an amino acid substitution at one or more amino acid positions corresponding to positions 280 and 269 of SEQ ID NO:1, wherein the HbAlc dehydrogenase has a lower oxidase activity and a lower ratio of oxidase activity to dehydrogenase activity (OX/DH) compared to the amadoriase prior to the amino acid substitution at one or more of amino acid positions corresponding to positions 280 and 269 of SEQ ID NO:1, wherein the amino acid at the position corresponding to position 280 of the amino acid sequence of SEQ ID NO: 1 is substituted with glutamine; or wherein the amino acid at the position corresponding to position 269 of the amino acid sequence of SEQ ID NO: 1 is substituted with methionine or leucine, and wherein the electron mediator that is not oxygen is selected from the group consisting of a colorimetric substrate, 1-methoxy-5-methylphenazinium methylsulfate (methoxy PMS), PMS, quinones, phenazines, viologens, cytochromes, phenoxazines, phenothiazines, ferricyanides, potassium ferricyanide, ferredoxins, ferrocenes, and osmium complexes. comprises an amino acid sequence having 90% or higher sequence identity with the amino acid sequence as shown in SEQ ID NO: 14 over the full length and comprises an amino acid substitution at one or more amino acid positions corresponding to positions 62, 63, 64, 68, 99, 102, 106, 110, 113, 355, 356 and 419 of the amino acid sequence of SEQ ID NO:1, and comprises an amino acid substitution at one or more amino acid positions corresponding to positions 280 and 269 of SEQ ID NO:1, wherein the HbAlc dehydrogenase has a lower oxidase activity and a lower ratio of oxidase activity to dehydrogenase activity (OX/DH) compared to the amadoriase prior to the amino acid substitution at one or more of amino acid positions corresponding to positions 280 and 269 of SEQ ID NO:1, wherein the amino acid at the position corresponding to position 280 of the amino acid sequence of SEQ ID NO: 1 is substituted with glutamine; or wherein the amino acid at the position corresponding to position 269 of the amino acid sequence of SEQ ID NO: 1 is substituted with methionine or leucine, and wherein the electron mediator that is not oxygen is selected from the group consisting of a colorimetric substrate, 1-methoxy-5-methylphenazinium methylsulfate (methoxy PMS), PMS, quinones, phenazines, viologens, cytochromes, phenoxazines, phenothiazines, ferricyanides, potassium ferricyanide, ferredoxins, ferrocenes, and osmium complexes.