Branched-chain amino acids and the association with type 2 diabetes

The prevalence of type 2 diabetes is soaring worldwide and is now recognized as one of the main threats to human health being associated with comorbidities, such as cardiovascular disease. Type 2 diabetes is a condition characterized by abnormalities in carbohydrate, lipid and protein metabolism, with the most characteristic features being hyperglycemia and dyslipidemia. The underlying pathological aberrations comprise insulin resistance and bihormonal dysfunction of the pancreatic aand b-cells. As aforementioned, high-protein diets are associated with impaired glucose tolerance, insulin resistance and an increased incidence of type 2 diabetes. Protein consists of amino acids (AAs). AAs were traditionally classified as essential or nonessential for humans and animals. Essential AAs cannot be synthesized from other compounds in the body at the level required for normal growth, so they must be obtained from food. Leucine, isoleucine and valine are named as branchedchain amino acids (BCAAs). BCAAs are the most abundant of the essential AAs. Leucine is the most abundant BCAA in many dietary proteins, accounting for over 20% of total dietary protein obtained from the human diet. Of the AAs studied, the BCAAs have generated the most research interest, as they have emerged as potential biomarkers of metabolic disease. Circulating levels of BCAAs are elevated in individuals with obesity, impaired fasting glucose and type 2 diabetes. Furthermore, circulating levels of BCAAs have the potential to predict development of type 2 diabetes.