NRG4 and type 2 diabetes mellitus: (Table 1) Several studies have shown that serum Nrg4 values were significantly elevated in patients with type 2 diabetes mellitus (T2DM) compared to healthy controls and were positively correlated with serum glucose levels (Kang et al., 2016; Chen et al., 2017b; Kocak et al., 2019), while Zhang et al. (Zhang et al., 2017) suggested that Nrg4 levels were significantly decreased in newly diagnosed T2DM.