Systems for rapid and accurate analyte measurement are described. For example, periodic glucose measurements can be achieved with high accuracy in a critical care environment by drawing blood into a device more than once per hour, analyzing blood (for example using infrared radiation through plasma). Safety and accuracy can be achieved by improved fluid control and avoidance of clotting. Data can be conveyed (e.g., displayed) to a user. A user can be allowed to annotate the data. For example, a touchscreen or other interface can allow addition of notes on a running graph of data, indicating events or other items of interest that may correspond to data readings or to particular times.
