Abstract: Blood glucose levels of a person are determined by a device which provides a light pattern which varies in regard to one or several parameters defining its luminance, color, rate of flicker, spatial contrast, detail content, speed or otherwise provided that the pattern has first and second appearances and can be shifted from one appearance to the other by changing one or more parameters. A person observes the light pattern and a subjective visual effect which correlates with a corresponding blood glucose level. Thus, the person's glucose level is accurately determined in a completely non-invasive manner.

Abstract: Blood glucose levels of a person are determined by a device which provides a changing light pattern which changes in regard to one or several parameters defining its luminance, color, rate of flicker, spatial contrast, detail content, speed or otherwise provided that the change gradually stimulates one retinal system more than another retinal system. A person observes the changing light pattern until a subjective visual effect occurs, which is preferably an observer perceived dramatic change in the appearance of the light pattern, for example a change in the perceived direction of rotation. The subjective visual effect indicates a specific ratio of stimulation of the two retinal systems, for example the point of balanced stimulation of the two systems.