Disclosed are a sugar-responsive gel and a medicine administering device having a pKa more suitable for use in a body environment and capable of administering medicine more autonomously than before. A sugar-responsive gel and an insulin administering device having a pKa more suitable for use in a body environment and capable of administering insulin more autonomously than before, wherein under a body condition of pKa of 7.4 or less and temperature of 35°C-40°C, when the glucose concentration increases, insulin can be released from a gel body in response thereto, and when the glucose concentration decreases, insulin release from the gel body can be suppressed.
