Glucose-sensitive microcapsules, whose volume changed in response to glucose, were successfully prepared by encapsulating glucose oxidase (GO(x)) into poly(L-lysine-alt-terephthalic acid) (PPL) microcapsules. The GO(x)-PPL microcapsules decreased in size in a glucose solution, after a certain lag time. The shrinking rate of the capsules showed a linear correlation with glucose concentration, while the lag time showed a logarithmical correlation with the glucose concentration.