Patent ID: 6653091
Filing Date: 2003-11-25
Classification: A61B,Y10S,Y10T

Abstract:
A method for measuring glucose present in a biological system, said method comprising:transdermally extracting a sample comprising glucose from the biological system using a sampling system that is in operative contact with a skin or mucosal surface of said biological system; obtaining a raw signal from the extracted glucose, wherein said raw signal is specifically related to glucose amount or concentration in the biological system; performing a calibration which correlates the raw signal with a measurement value indicative of the amount or concentration of glucose present in the biological system at the time of extraction; repeating said transdermal extracting and said obtaining a raw signal to obtain a series of two or more measurement values at selected time intervals; and predicting a measurement value based on the series of measurement values using a Mixtures of Experts algorithm comprising the following â€ƒBG=w1BG1+w2BG2+w3BG3â€ƒâ€ƒ(15)â€ƒwherein (BG) is blood glucose, BGi is the blood glucose predicted by Expert i; wi is a weighting value, and the individual Experts BGi are further defined by the expression shown as Equations 16, 17, and 18 BG1=p1(timec)+q1(active)+r1(signal)+s1(BG|cp)+t1â€ƒâ€ƒ(16) BG2=p2(timec)+q2(active)+r2(signal)+s2(BG|cp)+t2â€ƒâ€ƒ(17) â€ƒBG3=p3(timec)+q3(active)+r3(signal)+s3(BG|cp)+t3â€ƒâ€ƒ(18)â€ƒwherein, BGi is the blood glucose predicted by Expert i; parameters include, timec (elapsed time from a calibration of said sampling system), active (active signal), signal (calibrated signal), and BG/cp (blood glucose value at a calibration point); pi, qi, ri, and si are coefficients; and ti is a constant; and further where the weighting value, wi, is defined by the formulas shown as Equations 19, 20, and 21 w1=&ee;d1&ee;d1+&ee;d2+&ee;d3(19)w2=&ee;d2&ee;d1+&ee;d2+&ee;d3(20)w3=&ee;d3&ee;d1+&ee;d2+&ee;d3(21)â€ƒwhere e refers to the exponential function and di is a parameter set used to determine the weights wi, given by Equations 19, 20, and 21, and d1=&tgr;1(timec)+&bgr;1(active)+gamma1(signal)+&dgr;1(BG|cp)+&egr;1â€ƒâ€ƒ(22) â€ƒd2=&tgr;2(timec)+&bgr;2(active)+gamma2(signal)+&dgr;2(BG|cp)+&egr;2â€ƒâ€ƒ(23)d3=&tgr;3(timec)+&bgr;3(active)+gamma3(signal)+&dgr;3(BG|cp)+&egr;3â€ƒâ€ƒ(24) â€ƒwhere &tgr;i, &bgr;i, gammai and &dgr;i are coefficients, and where &egr;i is a constant.