To investigate the association of omentin-1 and inflammatory factors in serum and visceral adipose tissue (VAT) of women with gestational diabetes mellitus (GDM) compared to normal pregnant (NP) subjects. Furthermore, to examine their correlation with maternal clinical characteristics.We compared 116 GDM women to 115 NP women, at the time of cesarean section. Circulating omentin-1 and pro-inflammatory (IL-1β, IL-6, TNF-α), and anti-inflammatory cytokines (IL-1RA, IL-10) were examined. Moreover, their mRNA expression in VAT, along with inflammatory factors involved in the NF-κB pathway (TLR2, TLR4, NF-κB, IKκB), were examined.Circulating omentin-1 (p = 0.022) was lower and circulating IL-1-β, IL-1RA, as well as IL-10 (p = 0.005, p = 0.007, and p = 0.015, respectively), were higher in GDM compared to NP women. Omentin-1 correlated negatively with pre-pregnancy and gestational BMI, and HOMA-IR in all women, but was not associated with cytokines. TLR2, TLR4, IL-1β, IL-1RA, IL-6, IL-10 mRNA expression in VAT was lower in GDM compared with controls (p