POSTPRANDIAL HYPERGLYCEMIA MARKER, METHOD OF MEASURING THE SAME, AND USAGE THEREOF

• US 20100190194A1
• Filed: 08/10/2007
• Published: 07/29/2010
• Est. Priority Date: 08/11/2006
• Status: Active Grant

• Current Assignee: ARKRAY, Inc
• Original Assignee: ARKRAY, Inc
• Inventors: Imai, Toshihiro, Yonehara, Satoshi
• Granted Patent: US 8,637,275 B2
• Time in Patent Office: Days
• US Class Current: 435/18
• CPC Class Codes: G01N 2030/027 Liquid chromatography
• CPC Class Codes: G01N 2333/906 acting on nitrogen containing compounds as donors (1.4, 1.5, 1.7)
• CPC Class Codes: G01N 27/447 using electrophoresis
• CPC Class Codes: G01N 2800/042 Disorders of carbohydrate metabolism, e.g. diabetes, glucose metabolism
• CPC Class Codes: G01N 33/723 Glycosylated haemoglobin

Abstract

A new method of diagnosing postprandial hyperglycemia by indirectly measuring a blood glucose level is provided. Postprandial hyperglycemia is detected by measuring a glycation degree of lysine in hemoglobin, in which a side chain amino group of lysine is glycated (GHbLys %). Measurement of GHbLys % can be performed by cleaving hemoglobin by protease, treating a glycated part of a lysine residue in the obtained cleavage product of hemoglobin with fructosyl amino acid oxidase, and measuring a redox reaction between the glycated part and fructosyl amino acid oxidase.

Claims

1. A postprandial hyperglycemia marker for diagnosing postprandial hyperglycemia, wherein the postprandial hyperglycemia marker comprises hemoglobin having a glycated lysine residue.

2. The postprandial hyperglycemia marker according to claim 1, wherein the postprandial hyperglycemia marker is an average blood glucose level marker reflecting a postprandial blood glucose level.

3. A method of measuring a postprandial hyperglycemia marker, wherein the marker is a postprandial hyperglycemia marker according to claim 1, and a measurement of the postprandial hyperglycemia marker is a measurement of a glycation degree of a lysine residue of hemoglobin.

4. The method of measuring according to claim 3, wherein a method of measuring the glycation degree of the lysine residue is at least one selected from the group consisting of a high-performance liquid chromatography method, an immunization method, an enzymatic method, and an electrophoresis method.

5. The method of measuring according to claim 3, wherein a method of measuring the glycation degree of the lysine residue is an enzymatic method, and comprises following processes (A) to (C):

(A) a process of cleaving hemoglobin by protease;

(B) a process of treating a glycated part of a lysine residue in an obtained cleavage product of hemoglobin with fructosyl amino acid oxidase; and

(C) a process of determining the glycation degree of the lysine residue of hemoglobin by measuring a redox reaction between the glycated part and fructosyl amino acid oxidase.

6. The method of measuring according to claim 5, wherein the cleavage product of hemoglobin contains at least one selected from the group consisting of lysine, glycated lysine, peptide containing a lysine residue, and peptide containing a glycated lysine residue.

7. The method of measuring according to claim 5, wherein the cleavage product of hemoglobin contains peptide having 2 to 6 amino acid residues.

8. The method of measuring according to claim 3, wherein the method of measuring is a method of detecting the postprandial hyperglycemia marker contained in a sample, and

the sample is a whole blood sample, a hematocyte sample, or a hemolysis sample thereof.

9. The method of measuring according to claim 3, wherein the glycation degree of lysine of hemoglobin is calculated from a total amount of hemoglobin and an amount of hemoglobin having a glycated lysine residue.

10. The method of measuring according to claim 9, wherein the amount of hemoglobin having a glycated lysine residue is a glycation amount of the lysine residue.

11. A method of determining a risk for a specimen to develop diabetes, wherein the method of determining a risk comprises following process (a):

(a) a process of measuring a postprandial hyperglycemia marker, wherein the postprandial hyperglycemia marker comprises hemoglobin having a glycated lysine residue, by measuring a glycation degree of a lysine residue of hemoglobin by a method of measuring according to claim 3 with respect to a blood sample obtained from the specimen.

12. The method of determining a risk according to claim 11, further comprising process (b):

(b) a process of determining a risk for the specimen to develop diabetes by at least one method selected from the group consisting of (b1) to (b5) using the glycation degree of the lysine residue of hemoglobin measured in the process (a);

(b1) setting a boundary value between a glycation degree of a lysine residue of hemoglobin in blood collected from a healthy subject and a glycation degree of a lysine residue of hemoglobin in blood collected from a postprandial hyperglycemia patient as an evaluation criterion, and

determining the risk for developing diabetes being relatively high in a case where the glycation degree of the lysine residue of the specimen measured in the process (a) is relatively higher than the evaluation criterion;

(b2) setting a calculation value of a glycation degree of a lysine residue of hemoglobin, which is obtained by substituting a blood glucose level of blood collected from the specimen in the fasting state into a relational expression between a glycation degree of a lysine residue of hemoglobin in blood collected from a healthy subject and a blood glucose level of blood collected from a healthy subject in the fasting state, as an evaluation criterion, and

determining the risk for developing diabetes being relatively high in a case where the glycation degree of the lysine residue of the specimen measured in the process (a) is relatively higher than the evaluation criterion;

(b3) setting a blood glucose level of blood collected from the specimen in the fasting state as an evaluation criterion,

on the other hand, obtaining a calculation value of the blood glucose level of the specimen in the fasting state by substituting the glycation degree of the lysine residue of the specimen measured in the process (a) into a relational expression between a glycation degree of a lysine residue of hemoglobin in blood collected from a healthy subject and a blood glucose level of blood collected from a healthy subject in the fasting state, and determining the risk for developing diabetes being relatively high in a case where the calculation value of the blood glucose level of the specimen in the fasting state is relatively higher than the evaluation criterion;

(b4) setting a calculation value of a glycation degree of a lysine residue of hemoglobin, which is obtained by substituting a glycation degree of a 13 chain N-terminal amino acid residue of hemoglobin in blood collected from the specimen into a relational expression between a glycation degree of a lysine residue of hemoglobin in blood collected from a healthy subject and a glycation degree of a 13 chain N-terminal amino acid residue of hemoglobin in blood collected from a healthy subject, as an evaluation criterion, and

determining the risk for developing diabetes being relatively high in a case where the glycation degree of the lysine residue of the specimen measured in the process (a) is relatively higher than the evaluation criterion; and

(b5) setting a glycation degree of a β

chain N-terminal amino acid residue of hemoglobin in blood collected from the specimen as an evaluation criterion, on the other hand, obtaining a calculation value of the glycation degree of a β

chain N-terminal amino acid residue of hemoglobin of the specimen by substituting the glycation degree of the lysine residue of the specimen measured in the process (a) into a relational expression between a glycation degree of a lysine residue of hemoglobin in blood collected from a healthy subject and a glycation degree of a β

chain N-terminal amino acid residue of hemoglobin in blood collected from a healthy subject, and determining the risk for developing diabetes being relatively high in a case where the calculation value of the glycation degree of the β

chain N-terminal amino acid of hemoglobin is relatively higher than the evaluation criterion.

13. A method of diagnosing postprandial hyperglycemia of a specimen, wherein the method comprises the process (c):

(c) a process of measuring a postprandial hyperglycemia marker, wherein the postprandial hyperglycemia marker comprises hemoglobin having a glycated lysine residue, by measuring a glycation degree of a lysine residue of hemoglobin by a method of measuring according to claim 3 with respect to a blood sample obtained from the specimen

14. The method of diagnosing according to claim 13, further comprising process (d):

(d) a process of judging postprandial hyperglycemia of the specimen by at least one method selected from the group consisting of (d1) to (d5) using the glycation degree of the lysine residue of hemoglobin measured in the process (c);

(d1) setting a boundary value between a glycation degree of a lysine residue of hemoglobin in blood collected from a healthy subject and a glycation degree of a lysine residue of hemoglobin in blood collected from a postprandial hyperglycemia patient as an evaluation criterion, and

determining the specimen being postprandial hyperglycemia in a case where the glycation degree of the lysine residue of the specimen measured in the process (c) is relatively higher than the evaluation criterion;

(d2) setting a calculation value of a glycation degree of a lysine residue of hemoglobin, which is obtained by substituting a blood glucose level of blood collected from a specimen in the fasting state into a relational expression between a glycation degree of a lysine residue of hemoglobin in blood collected from a healthy subject and a blood glucose level of blood collected from a healthy subject in the fasting state, as an evaluation criterion, and

determining the specimen being postprandial hyperglycemia in a case where the glycation degree of the lysine residue of the specimen measured in the process (c) is relatively higher than the evaluation criterion;

(d3) setting a blood glucose level of blood collected from the specimen in the fasting state as an evaluation criterion,

on the other hand, obtaining a calculation value of the blood glucose level of the specimen in the fasting state by substituting the glycation degree of the lysine residue of the specimen measured in the process (c) into a relational expression between a glycation degree of a lysine residue of hemoglobin in blood collected from a healthy subject and a blood glucose level of blood collected from a healthy subject in the fasting state, and

determining the specimen being postprandial hyperglycemia in a case where the calculation value of the blood glucose level of the specimen in the fasting state is relatively higher than the evaluation criterion;

(d4) setting a calculation value of a glycation degree of a lysine residue of hemoglobin, which is obtained by substituting a glycation degree of a 13 chain N-terminal amino acid residue of hemoglobin in blood collected from the specimen into a relational expression between a glycation degree of a lysine residue of hemoglobin in blood collected from a healthy subject and a glycation degree of a 13 chain N-terminal amino acid residue of hemoglobin in blood collected from a healthy subject, as an evaluation criterion, and

determining the specimen being postprandial hyperglycemia in a case where the glycation degree of the lysine residue of the specimen measured in the process (c) is relatively higher than the evaluation criterion; and

(d5) setting a glycation degree of a 13 chain N-terminal amino acid residue of hemoglobin in blood collected from a specimen as an evaluation criterion, on the other hand, obtaining a calculation value of the glycation degree of the β

chain N-terminal amino acid residue of hemoglobin of the specimen by substituting the glycation degree of the lysine residue of the specimen measured in the process (a) into a relational expression between a glycation degree of a lysine residue of hemoglobin in blood collected from a healthy subject and a glycation degree of a β

chain N-terminal amino acid residue of hemoglobin in blood collected from a healthy subject, and

determining the risk being relatively high in a case where a calculation value of the glycation degree of the β

chain N-terminal amino acid of hemoglobin is relatively higher than the evaluation criterion.

15. A kit for measuring a marker used for a method of measuring a postprandial hyperglycemia marker according to claim 3, wherein the kit comprises protease, fructosyl amino acid oxidase, peroxidase, and a substrate developing a color by oxidation.

16. A kit for determining a risk used for a method of determining a risk of developing diabetes according to claim 11, wherein

the kit comprises protease, fructosyl amino acid oxidase, peroxidase, and a substrate developing a color by oxidation.

17. A kit for diagnosing postprandial hyperglycemia used for a method of diagnosing postprandial hyperglycemia according to claim 13, wherein

the kit comprises protease, fructosyl amino acid oxidase, peroxidase, and a substrate developing a color by oxidation.

18. A method of measuring an average blood glucose level reflecting a postprandial blood glucose level, wherein the method comprises following processes (x) and (y).

(x) a process of measuring an average blood glucose level marker measuring a glycation degree of a lysine residue of hemoglobin by a method of measuring a postprandial hyperglycemia marker according to claim 3 with respect to a blood sample obtained from a specimen, the average blood glucose level marker being a marker, wherein the postprandial hyperglycemia marker comprises hemoglobin having a glycated lysine residue,;

and

(y) a process of calculating the average blood glucose level reflecting a postprandial blood glucose level by substituting the glycation degree of the lysine residue of hemoglobin measured in the process (x) to a relational expression between a glycation degree of a lysine residue of hemoglobin and an average blood glucose level reflecting postprandial blood glucose level.