Determination of Plasma Amino Acid Biomarkers by High Performance Liquid Chromatography for Diagnosis of Type 2 Diabetes Mellitus

Abstract

The use of the fasting plasma glucose and 2-h plasma glucose tolerance tests leads to under-diagnosis of type 2 diabetes mellitus. To explore the contribution of metabolites for diagnosis for type 2 diabetes, plasma targeted metabolites (including free amino acids, lipids, and two hepatic aminotransferases) of 95 subjects were determined by high performance liquid chromatography and routine clinical methods. Receiver operating characteristic curve analysis was employed to evaluate potential diagnosis models. Based on the processing of orthogonal partial least squares-discriminant analysis, five amino acids (lysine, aspartate acid, threonine, methionine, and alanine) and two lipids (low density lipoprotein-cholesterol and high density lipoprotein-cholesterol) were discovered as potential biomarkers of type 2 diabetes. The area under the receiver operating characteristic curve built by the combination of these biomarkers and fasting plasma glucose was 0.994, which is significantly higher than that of the latter alone (0.907). These findings indicate that simultaneous measurement of specific metabolites with fasting plasma glucose from a single blood test for screening type 2 diabetes might be a more sensitive and specific strategy and provide additional insight regarding disease pathophysiologic mechanisms.

Keywords:

• Amino acid profile
• Aminotransferase
• HPLC
• Lipid
• Type 2 diabetes mellitus

Acknowledgments

We appreciate the work of the teams of Affiliated Hospital of Tianjin University of Traditional Chinese Medicine for the blood sample collections. This work was financially supported by the projects of National Natural Science Foundation of China (No. 90709014).

Notes

y = relative peak area; x = concentration, µmol/L.

Significance of group differences is given by *P < 0.05; **P < 0.01; and ***P < 0.001. Median, minimum, maximum, and the 95% CI of the median are computed based on the MedCalc software.

Significance of group differences is given by *P < 0.05; **P < 0.01; and ***P < 0.001. Amino acids are identified by their standards and concentrations are µmol/l quantified via internal standard (marked by a).

Note: The optimal cut-offs were automatically determined by SPSS version16.0 software based on ROC analysis for each metabolite.