The　cascaded　catalytic　reactions　of　glucose　oxidase　(GOx)　and　horseradish　peroxidase　(HRP)-like　nanozymes　have　been　extensively　used　for　the　colorimetric　detection　of　serum　glucose.　Nevertheless,　the　usage　of　biological　enzyme　and　the　adjustment　of　buffer　pH　due　to　the　inconsistent　pH　of　this　two-step　catalytic　reactions　are　involved　during　the　detection　of　serum　samples.　Herein,　the　photocatalysis　of　cyanamide-functionalized　carbon　nitride　(CACN)　with　high　efficient　electron-hole　separation　and　photoelectron　storage　ability　was　utilized　for　non-enzymatic　colorimetric　sensing　of　serum　glucose　without　the　need　to　adjust　the　buffer　pH　and　the　usage　of　biological　enzyme.　Under　the　irradiation　of　visible　light,　glucose　was　utilized　as　electron　donor　to　quench　the　photogenerated　holes　of　CACN　and　to　facilitate　the　reduction　of　2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide　(XTT)　by　the　photoelectrons　into　orange-yellow　product　(formazan).　The　absorbance　of　formazan　at　470　nm　showed　a　linear　response　toward　glucose　over　1.8–22.0　mmol　L−1　with　the　limit　of　detection　of　0.27　mmol　L−1　(S/N　=　3).　Furthermore,　the　digital　image　colorimetric　(DIC)　method　was　also　developed　by　a　portable　mobile.　Finally,　the　colorimetric　and　DIC　methods　were　utilized　for　the　detection　of　serum　glucose　with　high　accuracy,　reproducibility　and　recovery.　This　work　not　only　proposed　a　new　strategy　for　the　colorimetric　sensing　of　serum　glucose　but　also　extended　the　photocatalysis　of　carbon　nitride　application　in　the　field　of　biosensing.　©　2025　Elsevier　B.V.