Phenylboronic acids are known to form covalent complexes with polyol compounds such as glucose. A novel polyelectrolyte, containing phenylboronic acid as a glucose-sensitive moiety, has been synthesized and used for the fabrication of glucose-sensitive hollow polyelectrolyte capsules using the layer-by-layer technique. The response to glucose was observed as a rather fast dissolution of the capsules when brought into contact with a glucose-containing medium. These polyelectrolyte capsules are the first polyelectrolyte capsules able to respond to a stimulus that can be provided by the human body (i.e., an increase in glucose concentration). Therefore, the concept we present has promising applications in the biomedical field for the controlled delivery of insulin.