Placenta is the most accurate record of the infant prenatal experience. After delivery if the placenta is examined minutely, it provides much insight into the prenatal health of the baby and the mother. In diabetic pregnancy, placental weight is higher in comparison to normal pregnancy. To study the cellular differences that might contribute to larger size of placenta, light microscopic analysis was performed on 25 full term placentas, out of which 20 were of Gestational diabetes mellitus (12 controlled on diet, 8 controlled on insulin) and 5 control group. Tissue sections were processed and analyzed. Birth weight of neonate, placental weight, vascular pattern of chorionic blood vessels and site of attachment of umbilical cord were recorded. In the placenta of diabetic pregnants, gross abnormalities were uncommon but microscopic examination exhibited, to a varying degree, lesions like syncytial knots, fibrinoid necrosis, villous edema, villous fibrosis and capillary proliferation. These findings indicate that control of hyperglycemia only partially prevents the development of placental abnormalities which must be due to some other constituent factor of diabetic state.