TCF7L2 and type 2 diabetes mellitus: In conclusion, our prospective study documented, for the first time, an inverse and a positive association between high plasma allantoin levels, including allantoin-to-uric acid ratio and high xanthine-to-hypoxanthine ratio with incident T2D risk, respectively, in an elderly population at high cardiovascular risk, independently of the TCF7L2-rs7903146 polymorphism.