To　meet　the　increasing　need　for　point-of-care　testing　(POCT),　simple　and　portable　readout　strategies　would　be　highly　desirable.　Thermometer　with　high　accuracy　and　straightforward　readout　is　an　ideal　tool　for　the　development　of　new　POCT　methods.　The　exploration　of　new　thermometer-based　detection　methods　is　of　great　significance.　In　this　study,　a　simple　biosensor　for　glucose　based　on　the　photothermal　effect　of　gold　nanorods　using　a　simple　thermometer　as　readout　has　been　developed.　In　the　presence　of　glucose　oxidase,　glucose　can　react　with　the　dissolved　oxygen　to　produce　H2O2.　With　the　help　of　Fe2+,　H2O2　can　etch　gold　nanorods　(AuNRs)　to　different　aspect　ratios.　The　decrease　of　the　aspect　ratio　of　AuNRs　leads　to　the　blue-shift　of　the　localized　surface　plasmon　resonance　peak,　resulting　in　a　decrease　of　photothermal　effect　in　the　near-infrared　regions　and　the　temperature　of　the　system　decreased.　The　change　of　the　temperature　has　a　linear　relationship　with　the　logarithm　of　glucose　concentration　in　the　range　of　1.0–10.0　mM　with　a　detection　limit　of　0.8　mM.　The　proposed　method　possesses　a　bias　offset　of　−0.03　mM　for　glucose　detection　compared　to　the　hospital　method.　Since　many　enzymatic　reactions　can　produce　H2O2,　the　principle　can　be　modified　to　detect　different　targets　by　simply　change　of　the　enzyme　used.　©　2021　Elsevier　B.V.