LAUSR

Accumulating findings have evidenced that adipose tissuederived factors play crucial roles in the process of modulating systemic metabolism [1, 2]. Brown adipose tissue (BAT), traditionally known for consuming energy in response to cold [3], recently has been demonstrated to have an endocrine role in regulating fuel metabolism and energy balance [4–6]. Fibroblast growth factor 21(FGF21) and neuregulin 4 (Nrg4) are among the factors secreted by BAT [7, 8]. Wang et al. found that Nrg4 preserves glucose and lipid homeostasis through attenuating hepatic lipogenic signaling in obesity [8]. Another study via Nrg4 gene transfer in mice demonstrated that increased Nrg4 expression inhibits diet-induced chronic inflammation, improves insulin resistance, and prevents weight gain [9]. Moreover, circulating Nrg4 concentrations are inversely associated with the risk of metabolic syndrome in obese Chinese adults [10]. Controversially, Chen et al. found that circulating Nrg4 level was elevated in type 2 diabetes mellitus (T2DM) and showed positive correlation with adiposity index [11]. In this study, we aimed to assess the association between serum Nrg4 levels and T2DM.