Catalyzes the two-electron reduction of urocanate to dihydrourocanate (also named imidazole propionate or deamino-histidine). Dihydrourocanate is present at higher concentrations in subjects with type 2 diabetes, and directly impairs glucose tolerance and insulin signaling at the level of insulin receptor substrate (IRS) through activation of p38 gamma (MAPK12)-p62-mTORC1. Therefore, the UrdA enzyme from the gut bacteria E.lenta strain DSM 2243 may contribute to the pathogenesis of type 2 diabetes by producing the microbial metabolite dihydrourocanate. A + dihydrourocanate = AH2 + urocanate Binds 1 FAD per subunit. Binds 1 FMN covalently per subunit. Predicted to be exported by the Tat system. The position of the signal peptide cleavage has not been experimentally proven. E.lenta strain DSM 2243 is significantly more abundant in subjects with type 2 diabetes (T2D) compared with subjects with normal glucose tolerance (NGT). Belongs to the FAD-dependent oxidoreductase 2 family. FRD/SDH subfamily.