Glucose- Responsive Microgels for Closed Loop Insulin Delivery

Injectable insulin loaded microgels that are capable of modifying the amount of insulin released based on the patient's tissue glucose levels, methods for making and using these compositions have been developed. The microgels contain insulin, glucose oxidase entrapped in or bound to the microgels, and an agent that reduces hydrogen peroxide, entrapped in or bound to the microgels, wherein the polymeric microgel expands when pH decreases from physiological pH and shrinks when pH increases towards physiological pH, thereby releasing insulin at a rate corresponding to the glucose concentration. In one embodiment, the glucose oxidase and/or the agent reducing hydrogen peroxide are encapsulated in nanogels, then encapsulated within the microgel.