Abstract: The present disclosure relates to a continuous glucose monitoring biosensor, and more specifically, to: a biosensor which controls the flow of blood glucose flowing into a body during implantation, thereby enabling continuous detection and quantification of the blood glucose with high sensitivity; and a continuous glucose monitoring device and method using same. When a polymer blend composition including a hydrophilic polymer and a hydrophobic polymer according to the present disclosure, a diffusion control membrane formed therefrom and a continuous glucose monitoring biosensor including the same are used, they have the advantage capable of controlling an excessive influx of blood glucose due to an increase in the rate of diffusion in the sensor, thus enabling manufacture of a sensor having excellent accuracy and durability.