Dynamically restructuring pH-responsive hydrogels are synthesized, employing dynamic covalent chemistry between phenylboronic acid and cis-diol modified poly(ethylene glycol) macromonomers. These gels display shear-thinning behavior, followed by a rapid structural recovery (self-healing). Size-dependent in vitro controlled and glucose-responsive release of proteins from the hydrogel network, as well as the biocompatibility of the gels, are evaluated both in vitro and in vivo.