Disclosed is a method for fabricating a wearable hydrogel glucose sensor, belonging to the technical field of biomedical sensing, including using polyacrylamide hydrogel as a basic material, preparing a hydrogel film by adding with phenylboronic acid group capable of recognizing glucose molecules, and carrying out grating writing on the hydrogel film in a femtosecond laser direct writing mode to obtain the wearable hydrogel glucose sensor. The hydrogel film combines with glucose and expands linearly, which makes the grating period and effective refractive index change. The quantitative measurement of glucose is realized by detecting the spatial position of diffraction band and the change of diffraction power intensity.