A monitoring device adapted to be in contact with a tissue of a subject's body, the device comprising: a measuring unit, said measuring unit comprising: at least two light emitting sources configured to illuminate tissue adjacent to the light sources; and a plurality of sensors, configured to detect, at different positions along the tissue, radiation that is transmitted through the tissue and is reflected back from blood vessels in the tissue and from the content of the blood vessels as a result of the illumination emitted from the at least two light emitting sources; wherein the measuring unit is configured to measure the detected radiation; and a controller, coupled to the measuring unit, and receiving measurements therefrom, and configured to: drive the at least two light emitting sources to emit the illumination; derive from the measurements at least one absorption measurement of at least one respective component in the blood that comprises at least one of: albumin and triglycerides; associating a plurality of personal reflectance coefficients derived from the at least one absorption measurement with a corresponding plurality of subjects; analyze, from the measurements a concentration of glucose in the blood of the subject; wherein the analysis is personalized, based on the personal reflectance coefficients, and adjusted with respect thereto, and issue an alert when the concentration of glucose in the blood exceeds a predetermined threshold, wherein the device is configured as a wearable band that is adapted to be in contact with the tissue of the subject's body and is further configured to indicate the concentrations with respect to the personal reflectance coefficients. a measuring unit, said measuring unit comprising: at least two light emitting sources configured to illuminate tissue adjacent to the light sources; and a plurality of sensors, configured to detect, at different positions along the tissue, radiation that is transmitted through the tissue and is reflected back from blood vessels in the tissue and from the content of the blood vessels as a result of the illumination emitted from the at least two light emitting sources; at least two light emitting sources configured to illuminate tissue adjacent to the light sources; and a plurality of sensors, configured to detect, at different positions along the tissue, radiation that is transmitted through the tissue and is reflected back from blood vessels in the tissue and from the content of the blood vessels as a result of the illumination emitted from the at least two light emitting sources; wherein the measuring unit is configured to measure the detected radiation; and a controller, coupled to the measuring unit, and receiving measurements therefrom, and configured to: drive the at least two light emitting sources to emit the illumination; derive from the measurements at least one absorption measurement of at least one respective component in the blood that comprises at least one of: albumin and triglycerides; associating a plurality of personal reflectance coefficients derived from the at least one absorption measurement with a corresponding plurality of subjects; analyze, from the measurements a concentration of glucose in the blood of the subject; wherein the analysis is personalized, based on the personal reflectance coefficients, and adjusted with respect thereto, and issue an alert when the concentration of glucose in the blood exceeds a predetermined threshold, wherein the device is configured as a wearable band that is adapted to be in contact with the tissue of the subject's body and is further configured to indicate the concentrations with respect to the personal reflectance coefficients. drive the at least two light emitting sources to emit the illumination; derive from the measurements at least one absorption measurement of at least one respective component in the blood that comprises at least one of: albumin and triglycerides; associating a plurality of personal reflectance coefficients derived from the at least one absorption measurement with a corresponding plurality of subjects; analyze, from the measurements a concentration of glucose in the blood of the subject; wherein the analysis is personalized, based on the personal reflectance coefficients, and adjusted with respect thereto, and issue an alert when the concentration of glucose in the blood exceeds a predetermined threshold, wherein the device is configured as a wearable band that is adapted to be in contact with the tissue of the subject's body and is further configured to indicate the concentrations with respect to the personal reflectance coefficients.