Method of Measuring Insulin Resistance with Fatty Acid Combustion, and Composition Used Herein

• US 20160146791A1
• Filed: 03/13/2014
• Published: 05/26/2016
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Otsuka Pharmaceutical Company Limited (Otsuka Holdings Company Limited)
• Original Assignee: Otsuka Pharmaceutical Company Limited (Otsuka Holdings Company Limited)
• Inventors: Inada, Makoto, Kunizaki, Jun-ichi, Tobita, Kazuki, MOTONARI, Hiroshi, Sato, Tetsuya
• Granted Patent: US 10,444,229 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 5/0836 Measuring rate of CO2 production
• CPC Class Codes: G01N 2458/15 Non-radioactive isotope labels, e.g. for detection by mass spectrometry
• CPC Class Codes: G01N 2560/00 Chemical aspects of mass spectrometric analysis of biological material
• CPC Class Codes: G01N 33/497 of gaseous biological material, e.g. breath
• CPC Class Codes: G01N 33/5088 of vertebrates

Abstract

This invention provides a method for measuring insulin resistance of a test subject, and a composition suitably used for the method.

A method for measuring insulin resistance of a test act comprising steps (a) and (b) below, the method using a composition for measuring insulin resistance comprising, as an active ingredient, a C_12-38 fatty acid labeled with at least one isotope of C, wherein the C_12-38 fatty acid is converted in the body into labeled carbon dioxide that is excreted in expired air,

• • (a) intravenously administering the composition to a test subject and collecting expired air; and
  • (b) determining the ratio of labeled CO₂ amount to unlabeled CO₂ amount contained in the expired air or the ratio of labeled CO₂ amount to total CO₂ amount contained in the expired air.

Claims

1. A method for measuring insulin resistance of a test subject, comprising steps (a) and (b) below:

(a) intravenously administering a composition to a test subject and collecting expired air, the composition comprising, as an active ingredient, a C_12-38 fatty acid or a salt thereof labeled with at least one isotope of C, wherein the C_12-38 fatty acid or a salt thereof is converted in the body into labeled carbon dioxide that is excreted in expired air; and

(b) determining the ratio of labeled CO₂ amount to unlabeled CO₂ amount contained in expired air or the ratio of labeled CO₂ amount to total CO₂ amount contained in expired air.

2. The method for measuring insulin resistance according to claim 1, further comprising step (c) below:

(c) comparing “

the ratio of labeled CO₂ amount to unlabeled CO2 amount contained in expired air or the ratio of labeled CO₂ amount to total CO₂ amount contained in expired air”

obtained in the test subject in step (b) (test subject value) with “

the ratio of labeled CO₂ amount to unlabeled CO₂ amount contained in expired air or the ratio of labeled CO₂ amount to total CO₂ amount contained in expired air”

of a healthy subject (control value), and determining that the insulin sensitivity of the test subject is decreased (insulin resistance) when the test subject value is higher than the control value, and that the insulin sensitivity of the test subject is normal or not decreased when the test subject value is equivalent to or lower than the control value.

3. The method for measuring insulin resistance according to claim 1, wherein the test subject is a hyperinsulinemia patient, the method further comprising step (d) below:

(d) comparing “

the ratio of labeled CO₂ amount to unlabeled CO₂ amount contained in expired air or the ratio of labeled CO₂ amount to total CO₂ amount contained in expired air”

obtained in the test subject in step (b) (test subject value) with “

the ratio of labeled CO₂ amount to unlabeled CO₂ amount contained in expired air or the ratio of labeled CO₂ amount to total CO₂ amount contained in expired air”

of a healthy subject (control value), and determining that the test subject has “

insulin-nonresistant hyperinsulinemia”

in which the insulin sensitivity is normal or not decreased when the test subject value is lower than the control value.

4. The method for measuring insulin resistance according to claim 1, wherein the test subject is a hyperinsulinemia patient, the method further comprising step (e) below:

(e) comparing “

the ratio of labeled CO₂ amount to unlabeled CO₂ amount contained in expired air or the ratio of labeled CO₂ amount to total CO₂ amount contained in expired air”

obtained in the test subject in step (b) (test subject value) with “

the ratio of labeled CO₂ amount to unlabeled CO₂ amount contained in expired air or the ratio of labeled CO₂ amount to total CO₂ amount contained in expired air”

of a healthy subject (control value), and determining that the insulin sensitivity of the test subject is decreased, in other words, the test subject has “

insulin resistance”

or “

insulin-resistant hyperinsulinemia”

when the test subject value is higher than the control value, and determining that the insulin sensitivity of the test subject is normal or not decreased, in other words, the test subject has “

insulin-nonresistant hyperinsulinemia”

when the test subject value is lower than the control value.

5. The method for measuring insulin resistance according to any one of claims 1 to 4, wherein the isotope is ¹³C.

6. The method for measuring insulin resistance according to claim 5, wherein the C_12-38 fatty acid is a C_12-28 medium-chain, long-chain or very-long-chain fatty acid.

7. The method for measuring insulin resistance according to claim 6, wherein the C_12-38 fatty acid is at least one member selected from the group consisting of lauric acid, myristic acid, pentadecylic acid, stearic acid, oleic acid, and palmitic acid.

8. The method for measuring insulin resistance according to claim 1, wherein the test subject has at least one condition selected from the group consisting of borderline diabetes, type II diabetes, liver cirrhosis, non-alcoholic steatohepatitis, and non-alcoholic fatty liver disease.

9. A method for measuring a sugar/fatty acid combustion ratio in a test subject, using, as an index, a value (AUC_t[labeled C-glucose]/AUC_t[labeled C-fatty acid]) determined by dividing [an area under a Δ

-labeled C(‰

)-expired air collection time t curve] obtained by a glucose metabolism ability measurement method having steps (i) and (ii) below (hereinafter referred to as “

AUC_t[labeled C-glucose]”

) by [an area under a Δ

-labeled C(‰

)-expired air collection time t curve] obtained by the method for measuring insulin resistance according to any one of claims 1 to 4 (hereinafter referred to as “

AUC_t[labeled C-fatty acid]”

);

(i) Intravenously administering a composition to a test subject and collecting expired air, the composition comprising, as an active ingredient, glucose labeled with at least one isotope of C, wherein the glucose is converted in the body into labeled carbon dioxide that is excreted in expired air; and

(ii) determining the ratio of labeled CO₂ amount to unlabeled CO₂ amount contained in expired air or the ratio of labeled CO₂ amount to total CO₂ amount contained in expired air.

10. A method for measuring a sugar/fatty acid combustion ratio in a test subject, using, as an index, a value (1/blood glucose level/AUC_t[labeled C-fatty acid]) determined by dividing the reciprocal of a blood glucose level (1/blood glucose level) of the test subject by [an area under a Δ

-labeled C(‰

)-expired air collection time t curve] obtained by the method for measuring insulin resistance according to any one of claims 1 to 4 (herein referred to as “

AUC [labeled C-fatty acid]”

).

11. A method for measuring a sugar/fatty acid combustion ratio in a test subject using a value ([1/blood glucose level]/Ct[labeled C-fatty acid] (t=1-30 min)) determined by dividing the reciprocal of a blood glucose level (1/blood glucose level) of the test subject by Ct[labeled C-fatty acid] (t=1-30 min) of Δ

-labeled C(‰

) obtained by the method for measuring insulin resistance according to any one of claims 1 to 4.

12. A composition in an injectable dosage form for measuring insulin resistance, the composition comprising, as an active ingredient, a C_12-38 fatty acid or a salt thereof labeled with at least one isotope of C, wherein the C_12-38 fatty acid or a salt thereof is converted in the body into labeled carbon dioxide that is excreted in expired air.

13. The composition for measuring insulin resistance according to claim 12, wherein the isotope is ¹³C.

14. The composition for measuring insulin resistance according to claim 12 or 13, wherein the C_12-38 fatty acid is a C_12-18 saturated fatty acid or a C₁₈ unsaturated fatty acid.

15. The composition for measuring insulin resistance according to claim 14, wherein the C_12-38 fatty acid is at least one member selected from the group consisting of lauric acid, myristic acid, pentadecylic acid, stearic acid, oleic acid, and palmitic acid.