Plasma free amino acid profiles are associated with serum high molecular weight adiponectin levels in Japanese medical check-up population without type 2 diabetes mellitus

Abstract

Abstract To prevent the progression of type 2 diabetes mellitus (T2DM), early detection and intervention are important. Several studies have already shown that the serum adiponectin level could be useful for evaluating the future risk of T2DM. Recently, plasma free amino acid (PFAA) concentrations havealso emerged as potential biomarkers that predict the future onset of T2DM. In this study, we aimed to further characterise PFAA profiles by elucidating the association with the serum adiponectin level in this cross-sectional study. A total of 1,000 Japanese subjects who underwent medical check-upswere enrolled, and their plasma concentrations of 21 amino acids and clinical parameters were measured. The subjects without T2DM were divided into quartiles (Q1-4) by serum adiponectin level, andthe association between PFAA concentrations and the serum adiponectin level was analysed. Concentrations of glutamate, alanine, proline, tyrosine, histidine, methionine, lysine, branched-chain amino acids (BCAAs) and tryptophan varied significantly according to the adiponectin quartile. Furthermore, serum adiponectin levels showed significant inverse correlations with these amino acids. The change in the PFAA profile in the group with the lowest adiponectin concentrations (Q1) was similar to that of T2DM patients. Although both adiponectin levels and PFAA concentrations are known to be altered by the accumulation of visceral fat and insulin resistance, the levels of glutamate, BCAA, lysine and tryptophan remain significantly associated with adiponectin level after adjustment for age, body mass index and homeostasis model assessment of insulin resistance, showing the direct association between PFAA concentrations and the serum adiponectin level.