A recent meta-analysis of 18 published studies (Hu et al. 2019) notes that resistin levels are elevated in maternal circulation in gestational diabetes. Much less is known about the determinants of resistin abundance in the fetal circulation and current reports regarding the association between cord blood resistin with diabetes during pregnancy are discordant (Shang et al. 2018; Oncul et al. 2013; Mohamed et al. 2010). The present study found an increase in cord blood resistin in maternal diabetes, which agrees with the reports by Shang et al. and Oncul et al. (Shang et al. 2018; Oncul et al. 2013). We also demonstrated that resistin expression was highly enriched in cord blood mononuclear cells, suggesting that fetal mononuclear cells may be the main source of fetal circulating resistin. We, along with others (Chen et al. 2005; Erol et al. 2016), detect expression of resistin in the placenta. However, we found much lower abundance there compared to that in mononuclear cells. As no expression was detected in the placental trophoblast cell line, BeWo, we suspect that placental macrophages, rather than trophoblasts, are responsible for placental resistin expression.