Altered plasma levels of branched-chain amino acids (BCAAs) and aromatic amino acids (AAAs) may predict the development of insulin resistance and other type 2 diabetes mellitus (T2DM) associated comorbidities. To elucidate the role of plasma free amino acids (PFAAs) profile as a biomarker for early detection of diabetic kidney disease, quantitative measurement of PFAAs profile was determined for 90 T2DM subjects, 30 were free of nephropathy, 30 with microalbuminuria, 30 with macroalbuminuria, and in addition to 30 healthy controls. The plasma levels of valine, leucine, isoleucine, phenylalanine, citrulline, and total BCAAs were significantly increased in diabetic normoalbuminuria group when compared to controls. However, the total BCAAs level was significantly decreased in diabetic patients with micro and macroalbuminuria. Other amino acid plasma levels as tyrosine, arginine, ornithine, glycine, and the total AAAs level were significantly decreased in all diabetic subgroups compared to controls. Significant positive correlations between total BCAAs, valine, leucine, isoleucine, serum insulin, glucose, and HOMA-IR values in the diabetic normoalbuminuria group were found. The use of altered PFAAs profile as a prognostic factor in T2DM patients at risk for microalbuminuria or macroalbuminuria might reduce or prevent the incidence of end-stage diabetic renal disease.
Keywords: Diabetic kidney disease; Insulin resistance; Macroalbuminuria; Microalbuminuria; Plasma free amino acid profile; Type 2 diabetes mellitus.