Abstract: A device configured to determine a level or concentration of a disease-related analyte in a person's blood from volatile analyte(s) in the person's breath. The device includes one or more sensors configured to detect the volatile analyte(s) in the person's breath, a microcontroller in communication with each sensor, a transmitter, a battery, and a housing. The microcontroller contains logic that correlates parameter values from the sensor(s) or the level/concentration of the volatile analyte(s) to the level/concentration of the disease-related analyte. The transmitter is configured to transmit the parametric value from each sensor and/or the level/concentration of the volatile analyte(s) and/or the disease-related analyte. The housing surrounds, encloses and/or secures the sensor(s), the microcontroller, the transmitter and the battery, and contains a tube or opening through which the person exhales so that the person's breath contacts the sensor(s).