A non-invasive blood sensor includes a sensor body configured to mate with a tissue surface, light sources disposed on the sensor body, and a photodetector disposed on the sensor body in position for capturing light emanating from the tissue surface after emission from the blue light source by transmission, reflection or transflection. A non-invasive hemoglobin sensor includes blue, green and red light sources. A non-invasive WBC sensor includes green, red and infrared light sources. The light source(s) and photodetector(s) may be supported on a support structure configured to register with a corresponding portion of human anatomy in a predetermined fashion, to arrange them in a defined spatial relationship. The sensor or an integrated meter may include a controller programmed to receive signals from the photodetector and calculate blood hemoglobin and/or white blood cell counts as a function of the signals received from the photodetector(s) after emission by the light source(s).
