Although gestational diabetes usually resolves once the baby is born, unmanaged GD can have significant repercussions on both the mother and the baby. They range from the baby being born with low blood sugar and high weight, to having jaundice and in extreme cases being still born. The babies are also more likely to be obese and have diabetes later in life. The mother is at risk for diabetes later in life and seizures if GD is left untreated.
On one hand, it is easily treated and managed, and then it will go away after birth. On the other, it becomes dangerous for both mother and child if left untreated.