Abstract: The present invention allows for non-invasive monitoring of the blood sugar levels in diabetic patients. At least one heat and waterproof applicator is applied to the skin surface by a dosage pressure. Temporal dynamics of physiological parameters of the local tissue region are measured under the applicator. Temporal dynamics of climatic parameters of the environment are measured simultaneously or before the beginning of measurement of physiological parameters in the monitoring mode. Further, enthalpy of tissue is calculated with account for the influence of climatic parameters. Magnitude of thermal effect of metabolism of the local area of living tissue is calculated on the basic thermodynamics equation, connecting enthalpy of tissue with variables of thermodynamic state. Relative changes in the level of glucose are calculated in blood, proportional to the value of the thermal metabolism of the local area of living tissue.

Abstract: A method and apparatus for non-invasively testing analytical substances in turbid matrices i.e. body fluids and tissues. In this method a sample is irradiated with a beam of electromagnetic energy at two alternating wavelenths, .lambda..sub.1 and .lambda..sub.2, at which the absorption by the background is the same but at one of which the radiation is absorbed by the analyte and at the other it is not. The apparatus comprises means which enable to control the input energy at .lambda..sub.1 and .lambda..sub.2 so that at the output from the sample the electric signals issuing after detection cancel in the absence of the analyte in the sample. When analyte is present cancellation no longer occurs and a signal proportional to the analyte concentration in the sample is produced. The apparatus is also designed for shifting the response back to zero when a calibrating known concentration of analyte is used as standard, thus providing a controllable zeroing base line.