A method of non-invasive determination of a glucose concentration in blood based on the measurements of the total impedance of the skin of a patient is disclosed. The method is based on a linear model of a first order correlation between the glucose concentration and the total impedance, the model taking into account the rate of change of the glucose concentration. The coefficients used in an approximating function are determined at the preliminary stage measurements by an invasive method.
This application claims priority from a U.S. provisional patent application Ser. No. 60/266,774, filed Feb. 5, 2001, which is incorporated herein by reference.
A non-invasive method of monitoring a biological parameter concerning a bodily fluid of a subject, e.g., blood glucose of a human subject. The method includes: placing an electrode against a site of the skin of the subject; measuring impedance of the skin and determining the parameter therefrom; and using substantially the same site in another determination. Another non-invasive monitoring method includes: exposing a skin site to an aqueous salt solution for a pre-determined first period of time; removing excess of the solution from the site; measuring impedance at the site; exposing the site to the solution for a pre-determined second period of time and repeating the removing and measuring steps. It is determined whether the impedance measured falls within a pre-determined range. The latter exposure and removal steps are repeated, if necessary, until two consecutive impedance measurements within the pre-determined range are obtained.
A closed loop therapy system for controlling a concentration of a substance, such as blood glucose concentration, in the body of a user. The system and method employ a sensor system that measures a glucose level in the body, a controller that uses the measured glucose levels to generate an output that can be used to automatically or manually control an intradermal insulin infusion system to set a constant or time-varying profile of target blood glucose concentrations in a user, and then infuse an appropriate amount of insulin into the body of the user so as to reach and maintain the target values of the blood glucose concentration.
Disclosed are systems and methods of determining the amount of a substance in a living organism. In one embodiment, the method comprises: applying an electrical signature signal to the living organism, wherein the electrical signature signal corresponds to a predetermined amount of the substance; measuring the response of the living organism to the applied signature signal; and determining whether an elevated response has resulted from applying the electrical signature signal, if so, then determining the amount of the substance in the living organism from the predetermined amount of the substance.
