Abnormal circulating amino acid profiles in multiple metabolic disorders

- Disordered serum amino acid profiles exhibited consistent direction of relationship.
- Valine, Glutamic acid, Proline, and Isoleucine were concomitantly elevated.
- Glycine was significantly lowered in multiple metabolic disorders.

AimTo evaluate circulating amino acids (AA) profiles in obesity, type 2 diabetes (T2D) and metabolic syndrome (MetS).MethodsSerum AA were profiled among 200; healthy, obese, T2D and MetS subjects matched by sex, age and BMI using ultra-high performance liquid chromatography tandem quadruple mass spectrometry (UPLC-TQ-MS). A meta-analysis, including 47 case-control studies (including the current study) on serum AA in obesity, T2D and MetS searched through October 2016 was conducted to explore the AA differences in obesity, T2D and MetS.ResultsIn comparison with healthy controls, 14 AA (10 increased and 4 decreased) were significantly altered (P < 0.05) in all non-healthy subjects. Also, mean differences of valine (obese: 34.13 [27.70, 40.56]µmol/L, P < 0.001, T2D: 19.49 [3.31, 35.68]µmol/L, P < 0.05, MetS: 29.18 [16.04, 42.33]µmol/L, P < 0.001), glutamic acid (obese: 18.62 [11.64, 25.61]µmol/L, P < 0.001, T2D: 19.94 [0.28, 39.61]µmol/L, P < 0.05, MetS: 12.45 [3.98, 20.91]µmol/L, P < 0.001), proline (obese: 16.72 [6.20, 27.24]µmol/L, P < 0.001, T2D: 20.72 [15.82, 25.61]µmol/L, P < 0.001, MetS: 29.95 [25.18, 34.71]µmol/L, P < 0.001) and isoleucine (obese: 11.39 [8.54, 14.24]µmol/L, P < 0.001, T2D: 7.37 [1.52, 13.22]µmol/L, P < 0.05, MetS: 10.40 [4.90, 15.89]µmol/L, P < 0.001) were significantly higher compared to healthy controls. Similarly, mean differences of glycine (obese: −30.99 [−39.69, −22.29]µmol/L, P < 0.001, T2D: −30.37 [−41.80, −18.94]µmol/L, P < 0.001 and MetS: −35.24 [−39.28, −31.21]µmol/L, P < 0.001) were significantly lower compared to healthy controls.ConclusionIn both the case-control study and meta-analysis, obesity was related to the most circulating AA changes, followed by MetS and T2D. Valine, isoleucine, glutamic acid and proline increased, while Glycine decreased in all metabolic disorders.