Systems and methods for continuous measurement of a medicament in vivo are provided. In some embodiments, the system is configured to provide information associated with medicament titration and includes a continuous analyte sensor and a communication device. In some embodiments, the system is configured for continuous ambulatory drug testing, including an ambulatory host monitor having a continuous sensor, a location module, a processor module and a transmitter. In some embodiments, the system is configured for continuously monitoring a hormone level and includes a continuous hormone sensor and a communication device configured to output hormone information in real time. Yet another embodiment provides an analyte sensor for continuous monitoring of a host's nutritional status, and is configured for both continuous glucose detection and continuous albumin detection.