ALT Schematic diagram illustrating potential mechanisms suitable for glucose-dependent insulin release from glucose-responsive vesicles (A), which dissociate in the presence of high glucose concentrations due to the consequences of hypoxia generated by the metabolism of glucose by the enzyme glucose oxidase,13 and (B) from so-called smart gels losing their skin layer due to complex formation of phenylboronic acid with glucose (negatively charged) leading to hydration and dissolution of a skin layer around nanogels preventing insulin release.