There were significant differences in Nrg4 levels among the poorly controlled T2DM, the well-controlled T2DM, and the controls; Nrg4 was significantly correlated with fasting plasma glucose; a .1-point increase in Nrg4 levels was associated with a 4.4-fold increase of T2DM presence. Here, NRG4 is linked to type 2 diabetes mellitus.