The placenta is an organ between the mother and fetus necessary for fetal growth and development. Gestational diabetes mellitus (DM) is the most frequent metabolic condition detected during pregnancy. It is characterized as hyperglycemia of various severity with onset or first detection during pregnancy that does not clearly describe any form of preexisting diabetes. Urotensin II (UII), a pluripotent vasoactive peptide, is important in developing insulin resistance. This study aimed to determine the level of Urotensin II(UII) in placenta and in the serum of diabetic and nondiabetic women. Methods The blood and placenta tissue collected from 50 ladies had been enrolled in this research ( 25 females with uncomplicated), (25 women with gestational diabetes). Immunohistochemistry (IHC) was used to look at the expression of the Urotensin II (UII) marker in placenta specimens. The IHC analysis revealed that Urotensin II expression was primarily found in placental cytotrophoblast and the syncytiotrophoblast. Results of an immunohistochemistry investigation using the Urotensin II (UII) marker revealed a significant increase (p ≤ 0.001) in diabetic women’s placentas and serum than control groups. Conclusion, the Urotensin II is mainly located in the cytotrophoblast and syncytiotrophoblast. That was significantly higher in the gestational DM group.