Background– Published findings suggest that branched–chain amino acids (BCAAs), are associated with insulin resistance and type 2 diabetes. Other amino acids such as aromatic amino acids, glycine, glutamine, and glutamate have also been related to prediabetes and type 2 diabetes risk.

Objectives– To conduct a systematic review of prospective studies for evaluating effect of BCAAs on prediabetes.

Methodology– We searched pubmed, medline, and embase databases through November2017. We conducted meta–analysesof Prospective studies of BCAAs, with data estimates from at least 8 prospective studies and type 2 diabetes risk were conducted, and multivariable– adjusted relative risks of type 2 diabetes were calculated per study–specific SD difference in a given metabolite.

Results– We identified 19 prospective studies reporting associations of BCAAs and prediabetes& type 2 diabetes. We found 36% higher risk of type 2 diabetes per study–specific SD difference for iso–leucine (pooled relative risk 1.36 [1.24–1.48]; I2 = 9.5%), 36% for leucine (1.36 [1.17–1.58]; I2 = 37.4%), 35% for valine (1.35 [1.19–1.53]; I2 = 45.8%), 36% for tyrosine (1.36 [1.19–1.55]; I2 = 51.6%), and 26% for phenylalanine (1.26 [1.10– 1.44]; I2 = 56%).

Conclusion– Our results confirmed that, several branched chain amino acids are consistently associated with the risk of developing type 2 diabetes in pre–diabetic patients.