The purpose of this study is to examine the changes in the umbilical cord in women diagnosed with gestational diabetes mellitus In this study, as a control group human placental tissues from normotensive pregnancies was collected from diabetic women at 28-35 weeks of gestation. Gestational diabetes (n= 20) and normal umbilical cord (n= 20) for a total of 40 units were received. GDM groups compared to the control group was significantly higher values was detected (p<0.01). In GDM group, light microscopy showed erosion of the endothelium and complete rupture of the umbilical vessels resulting in extravasation of blood within Wharton's jelly. it was observed that the cytoplasmic fragments and cell infiltration of the spill to the subepithelial layer of apoptotic cell PECAM-1 positive reaction showed. E-Cadherin in endothelial side surface of diabetes group showed weak expression in the nucleus and showed positive reaction in smooth muscle.