Blood glucose monitoring system

A system for noninvasively monitoring blood glucose concentration within a patient's bloodstream via spectroscopic measurement of attenuation of a fleshy medium containing blood, said system comprising:

• a light source which emits optical radiation at a plurality of wavelengths;
• a variable optical filter which in a first position selectively passes a first subset of said plurality of wavelengths, said filter movable from a first position to a second position to pass a second subset of said plurality of wavelengths;
• an optical detector positioned to receive light from said light source which has been filtered by said filter and attenuated by said fleshy medium and said blood, said optical detector responsive to light wavelengths of at least said first and second subsets to generate an output signal indicative of the sum of intensities of the optical radiation filmed by said filter and attenuated by said fleshy medium and blood;
• and
• a signal processor coupled to said detector to receive said output signal;
• an isolation module executable by said signal processor to isolate portions of said output signal due to optical characteristics of said optical filter and due to said fleshy medium from portions of said output signal reflecting the optical characteristic of said blood to analyze said portions reflecting the optical characteristics of said blood to determine the concentration of glucose within said patient's bloodstream.

A method of noninvasively determining blood glucose concentration comprising the steps of:

• generating a set of values indicative of optical characteristics of significant blood constituents, one of said values indicative of the optical characteristics of glucose dissolved in water;
• illuminating a fleshy medium having blood with light of a plurality of wavelengths;
• detecting said light after attenuation of said light by said fleshy medium and said blood;
• generating a signal from said detected light, said signal indicative of optical characteristics of said fleshy medium and said blood;
• isolating components of said signal which are indicative of the concentration of glucose dissolved in water within said blood in response to said detected light and said set of values indicative of optical characteristics of said significant blood constituents;
• and
• generating a value indicative of the glucose concentration within said blood.

A method of noninvasively determining a concentration of a blood constituent comprising the steps of:

• illuminating a living medium having blood with optical radiation, wherein the blood has a concentration of the blood constituent and the optical radiation traverses at least one path length through the medium;
• detecting the optical radiation to produce electrical signals indicative of optical characteristics of the medium and the blood;
• in response to said electrical signals, generating a first set of values indicative of the optical characteristics of the medium and the blood;
• taking a logarithm of the first set of values to generate a second set of values;
• taking a logarithm of the second set of values to obtain a linearized set of values that are indicative of the concentration of the blood constituent;
• and
• calculating the concentration of the blood constituent based upon the linearized electrical signals.

A method of analyzing a concentration of a blood constituent from an optical signal incident upon a fleshy medium having blood, the method comprising the steps of:

• filtering the optical signal with a filter having known spectral characteristics;
• detecting the optical signal after attenuation from said fleshy medium to generate a signal having a set of values indicative of optical characteristics of the fleshy medium and said blood;
• removing components of the signal quantity due to electrical noise;
• removing components of the signal due to nonblood constituents of the fleshy medium;
• linearizing the signal to generate a set of linearly related values indicative of the concentration of the blood constituent;
• deconvolving components of the electrical signal due to the filter prior to the step of solving for the blood constituent concentration;
• and
• solving the linearly related values for the blood constituent concentration.

A method of analyzing a concentration of a blood constituent from an optical signal incident upon a fleshy medium having blood, the method comprising the steps of:

• detecting the optical signal after attenuation from said fleshy medium to generate a signal having a set of values indicative of optical characteristics of the fleshy medium and said blood;
• removing components of the signal quantity due to electrical noise;
• removing components of the signal due to nonblood constituents of the fleshy medium;
• linearizing the signal to generate a set of linearly related values indicative of the concentration of the blood constituent;
• generating a spectral library containing values indicative of spectral characteristics of components of the blood including the blood constituent;
• generating a set of linear equations having coefficients based upon said values indicative of the spectral characteristics of components of the blood;
• and
• solving the linear equations to obtain a value indicative of the concentration of the blood constituent.

A method of noninvasively determining a concentration of a blood constituent comprising the steps of:

• illuminating a living medium having blood with optical radiation, wherein the blood has a concentration of the blood constituent and the optical radiation traverses at least one path length through the medium;
• detecting the optical radiation to produce electrical signals indicative of optical characteristics of the medium and the blood;
• in response to said electrical signals, generating a first set of values indicative of the optical characteristics of the medium and the blood;
• taking a logarithm of the first set of values to generate a second set of values;
• taking a logarithm of the second set of values to obtain a linearized set of values that are indicative of the concentration of the blood constituent;
• and
• calculating the concentration of the blood constituent based upon the linearized set of values.

A method of noninvasively determining a concentration of a blood constituent comprising the steps of:

• illuminating a living medium having blood with optical radiation, wherein the blood has a concentration of the blood constituent and the optical radiation traverses at least one path length through the medium;
• filtering the optical signals with a filter having known spectral characteristics;
• detecting the optical radiation after attenuation through said living medium and said blood to produce electrical signals indicative of the optical characteristics of the medium and the blood;
• linearizing the electrical signals;
• deconvolving components of the electrical signal due to the filter;
• and
• calculating the concentration of the blood constituent based upon the linearized and deconvolved electrical signals.