The method uses the antigen-antibody reaction for the direct determination of hemoglobin A1c (HbA1c) in whole blood. Total hemoglobin and HbA1c compete for adsorption to latex particles (R1). Human anti-HbA1c monoclonal antibody (R2a) binds to the latex-HbA1c complex. The presence of goat anti-mouse IgG polyclonal antibody (R2b) causes the agglutination of latex particles (complexes). The amount of formed agglutination is proportional to the concentration of HbA1c in the sample and can be measured by turbidimetry.