Pregestational and gestational diabetes mellitus (GDM) can significantly impact maternal health during pregnancy. Pregestational diabetes increases the risk of complications such as preeclampsia, hypertension, and increased cesarean delivery rates. It also heightens the chances of developing diabetic ketoacidosis and worsens diabetic retinopathy and nephropathy. Gestational diabetes, on the other hand, can lead to macrosomia, shoulder dystocia, and an increased likelihood of cesarean delivery. Both types necessitate close monitoring to mitigate risks and optimize maternal and fetal outcomes.