title: Association between insulin resistance and plasma amino acid profile in non-diabetic Japanese subjects.
abstract: OBJECTIVE
  Elevation of the branched-chain amino acids (BCAAs), valine, leucine and isoleucine; and the aromatic amino acids, tyrosine and phenylalanine, has been observed in obesity-related insulin resistance. However, there have been few studies on Asians, who are generally less obese and less insulin-resistant than Caucasian or African-Americans. In the present study, we investigated the relationship between homeostasis model assessment of insulin resistance (HOMA-IR) and plasma amino acid concentration in non-diabetic Japanese participants.
  
  
  METHODS
  A total of 94 healthy men and women were enrolled, and plasma amino acid concentration was measured by liquid chromatography/mass spectrometry after overnight fasting. The associations between HOMA-IR and 20 amino acid concentrations, and anthropometric and clinical parameters of lifestyle-related diseases were evaluated.
  
  
  RESULTS
  The mean age and body mass index were 40.1 ± 9.6 years and 22.7 ± 3.9, respectively. Significantly positive correlations were observed between HOMA-IR and valine, isoleucine, leucine, tyrosine, phenylalanine and total BCAA concentration. Compared with the HOMA-IR ≤ 1.6 group, the HOMA-IR > 1.6 group showed significantly exacerbated anthropometric and clinical parameters, and significantly elevated levels of valine, isoleucine, leucine, tyrosine, phenylalanine and BCAA.
  
  
  CONCLUSIONS
  The present study shows that the insulin resistance-related change in amino acid profile is also observed in non-diabetic Japanese subjects. These amino acids include BCAAs (valine, isoleucine and leucine) and aromatic amino acids (tyrosine and phenylalanine), in agreement with previous studies carried out using different ethnic groups with different degrees of obesity and insulin resistance.
authors.affiliation: Tokai University Tokyo Hospital Tokyo, Japan.
authors.forename: Chizumi
authors.initials: C
authors.lastname: Yamada
authors.affiliation: Tokai University Tokyo Hospital Tokyo, Japan.
authors.forename: Masumi
authors.initials: M
authors.lastname: Kondo
authors.affiliation: Tokai University Tokyo Hospital Tokyo, Japan.
authors.forename: Noriaki
authors.initials: N
authors.lastname: Kishimoto
authors.affiliation: Department of Molecular Life Science, Division of Basic Medical Science and Molecular Medicine, Tokai University School of Medicine Tokyo, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Shibata
authors.affiliation: Department of Molecular Life Science, Division of Basic Medical Science and Molecular Medicine, Tokai University School of Medicine Tokyo, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Nagai
authors.affiliation: Department of Molecular Life Science, Division of Basic Medical Science and Molecular Medicine, Tokai University School of Medicine Tokyo, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Imanishi
authors.affiliation: Life Care Center, Graduate School of Medicine, Tokai University Tokyo, Japan.
authors.forename: Takashige
authors.initials: T
authors.lastname: Oroguchi
authors.affiliation: Department of Molecular Life Science, Division of Basic Medical Science and Molecular Medicine, Tokai University School of Medicine Tokyo, Japan ; Life Care Center, Graduate School of Medicine, Tokai University Tokyo, Japan.
authors.forename: Naoaki
authors.initials: N
authors.lastname: Ishii
authors.affiliation: Tokai University Tokyo Hospital Tokyo, Japan ; Life Care Center, Graduate School of Medicine, Tokai University Tokyo, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Nishizaki
keywords: Amino acids; Homeostasis model assessment of insulin resistance; Insulin resistance