A system for continuous in vivo biosensing of specific analyte molecule concentrations based on the dynamic optical properties of electronic polymers is disclosed. The biosensor system includes at least one implant member subcutaneously exposed to the interstitial fluid of the subject, and a reader member at least temporarily positioned over the implant member to probe it with light of specific wavelengths through the skin. The system has many potential applications, including the real-time monitoring of blood glucose levels in diabetics as a method to supplement or replace conventional capillary blood testing.