Amino Acid (Leucine) Chromatography: A Study of Branched-Chain Aminoaciduria in Type 2 Diabetes

Introduction Diabetes is a disease characterized by insulin deficiency resulting in glucose intolerance and in abnormalities of other metabolic fuels including protein. Recently, a number of studies have revealed that branched-chain amino acids (BCAAs) (leucine, isoleucine, and valine) play an important role in the regulation of protein synthesis by activating mammalian target of rapamycin (mTOR) in pancreatic beta cells. BCAAs have positive effects on the regulation of glucose homeostasis. Leucine is an important nutrient signal as evidenced by recent observations, which showed increased fasting concentrations of circulating BCAAs being associated with an increased risk of type 2 diabetes (T2D) and insulin resistance in humans. Leucine seems to have direct effects on hypothalamic and brainstem functioning involved in satiety, which can potentially contribute to obesity and T2D. A number of observational studies indicate that elevated activity of BCAAs could be associated with poor metabolic health and T2D complications. Although these associations were consistently observed in humans, the mechanisms underlying this relationship remain to be completely understood. In this study, we have attempted to evaluate urinary excretion of leucine among patients of T2D and compared them with healthy controls by using a low-cost and non-invasive amino acid chromatography technique. Methods The study was carried out in the Department of Biochemistry, Central Research Unit, Prathima Institute of Medical Sciences (PIMS), Karimnagar, Telangana, India, during the period between July and September 2016. A group of 55 normal healthy subjects (control group A), and 55 patients suffering from T2D on treatment (test group B), were enrolled in the study. The urine samples were collected from normal and T2D subjects. Thin-layer chromatography (TLC) for leucine was performed on all the urine samples. Results A strong correlation (p=0.0004) was found between the urinary excretion of leucine among the control (Rf=0.174 +/- 0.089) and T2D (Rf=0.247 +/- 0.030) patients. Conclusion Excretion of BCAAs (leucine) in detectable and increased quantities reflect the presence of an altered metabolic state attributable to T2D, which in turn could lead to early diabetic complications. This method (TLC), being non-invasive and cost-effective, could be recommended for assessing the progression and management of type 2 diabetes patients.