Optical method and device for determining blood glucose levels

• US 6,113,537 A
• Filed: 10/15/1997
• Issued: 09/05/2000
• Est. Priority Date: 04/19/1996
• Status: Expired due to Term

• Current Assignee: Jaime A. Castano
• Original Assignee: Jaime A. Castano
• Inventors: Castano, Jaime A.
• Primary Examiner(s): Dvorak, Linda C. M.
• Assistant Examiner(s): YARNELL, BRYAN KEITH
• Application Number:
  US08/950,817
• Time in Patent Office: 1,056 Days
• Field of Search: 600/300, 600/301, 600/310, 600/316, 600/319, 600/558, 128/897, 128/898, 351/206, 351/222, 351/223, 351/239, 351/244, 356/23, 356/25
• US Class Current: 600/300
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/161 Flicker fusion testing eye testing A61B3/00

Abstract

Blood glucose levels of a person are determined by a device which provides a light pattern which varies in regard to one or several parameters defining its luminance, color, rate of flicker, spatial contrast, detail content, speed or otherwise provided that the pattern has first and second appearances and can be shifted from one appearance to the other by changing one or more parameters. A person observes the light pattern and a subjective visual effect which correlates with a corresponding blood glucose level. Thus, the person'"'"'s glucose level is accurately determined in a completely non-invasive manner.

Claims

1. A method for measuring a blood glucose concentration of a subject, said method comprising:

a) providing a light pattern which provides a first subjective characteristic and a second subjective characteristic, and can be varied from said first characteristic to said second characteristic by varying a visual parameter from a first value to a second value, said pattern having a crossover point at which said characteristic changes from said first subjective characteristic to said second subjective characteristic, where the value of said parameter at said crossover point varies with the blood glucose concentration of said subject;

b) allowing said subject to observe said subjective visual characteristic of said light pattern; and

c) correlating said subjective visual characteristic with said subject'"'"'s blood glucose concentration.

2. The method of claim 1, wherein said pattern comprises an alternation between high luminance and low luminance, and said parameter comprises a difference between said high luminance and low luminance.

3. The method of claim 1, wherein said pattern comprises an alternation between high luminance and low luminance, and said parameter comprises a frequency of alternation.

4. The method of claim 1, wherein at least a portion of said light pattern changes over time with respect to a parameter selected from the group consisting of color, luminance level, contrast, shape, size, position, detail content, texture, speed of movement, direction of movement and rate of flicker.

5. The method of claim 1, wherein said pattern comprises a plurality of regions, each region having a different value of a parameter selected from the group consisting of color, luminance level, contrast, shape, size, position, detail content, texture, speed of movement, direction of movement and rate of flicker.

6. A device for measuring a blood glucose level of a subject, said device comprising:

a body; and

display means contained within said body for generating a light pattern which provides a first subjective characteristic and a second subjective characteristic, and can be varied from said first characteristic to said second characteristic by varying a visual parameter from a first value to a second value, said pattern having a crossover point at which said characteristic changes from said first subjective characteristic to said second subjective characteristic, where the value of said parameter at said crossover point varies with the blood glucose concentration of said subject;

wherein said light pattern is selected so that it will have a first subjective visual appearance when the subject'"'"'s blood glucose level is below a predetermined concentration, and will have a distinctly different appearance when the subject'"'"'s blood glucose level is above said predetermined concentration.

7. The device of claim 6, wherein said display means comprises means for varying a parameter of said light pattern such that the said first subjective characteristic is changed to said second subjective characteristic.

8. The device of claim 7, further comprising:

actuation means, which is actuated to indicate observation of a subjective visual effect;

processor means, which is capable of measuring said parameter when actuated, and correlating said measured parameter with a corresponding blood glucose level; and

means for displaying information about blood glucose levels.

9. The device of claim 8, wherein said light pattern is selected from the group consisting of flickering light and rotating windmill images, and said subjective visual appearance is selected from the group consisting of appearance of colors, disappearance of colors, appearance of a regular geometric pattern, disappearance of a regular geometric pattern, appearance of perceived flicker, disappearance of perceived flicker, appearance of radial movement, disappearance of radial movement, and reversal in direction of rotation.

10. The device of claim 8, wherein said processor includes information on a range of parameter values associated with the presence of a subjective visual effect, along with the corresponding blood glucose levels for said subject.

11. The device of claim 8, wherein said processor is programmed to avoid erroneous measurements by making redundant measurements, checking the consistency of the subject'"'"'s responses, and canceling any effect created by the subject'"'"'s reaction time.

12. The device of claim 6, wherein said display means displays said light pattern in a plurality of regions, wherein each region displays said pattern with a different value of said parameter;

and further comprising;

actuator means, enabling the subject to indicate which region corresponds to a preselected visual characteristic.

13. The device of claim 12, wherein said light pattern comprises an alternation between high luminance and low luminance, and said parameter comprises an amount of contrast between said high luminance and low luminance.

14. The device of claim 12, wherein said light pattern comprises an alternation between high luminance and low luminance, and said parameter comprises a frequency of alternation.

15. The device of claim 12, wherein said light pattern comprises a plurality of radial vane patterns, and said first and second subjective visual characteristics comprise direction of rotation.

16. A method for measuring a blood glucose concentration of a subject, said method comprising:

a) measuring a sensitivity of a subject'"'"'s visual system to alternating changes in luminance to obtain a value representing the sensitivity; and

b) inferring from the value a blood glucose level of the subject.

17. The method of claim 16, wherein said inferring comprises comparing said value to a calibration datum.

18. The method of claim 16, wherein said measuring comprises determining the ability of the subject to detect flicker.