Final answer:
The nurse should slowly decrease the IV rate to prevent hypoglycemia and check the newborn's blood glucose levels every 1 to 2 hours for potential hyperglycemia after stopping the IV.
Step-by-step explanation:
When preparing to discontinue the IV for a newborn whose mother has type 1 diabetes, the nurse should decrease the rate slowly. This is necessary because an abrupt cessation can lead to hypoglycemia due to the baby's body having been receiving a steady supply of glucose through the IV. The nurse should also check for elevated blood glucose levels every 1 to 2 hours after discontinuing the IV to monitor for potential hyperglycemia, which can occur as the baby adjusts to not having the continuous glucose infusion. It is not indicated to monitor for metabolic alkalosis or withhold oral feedings in this scenario specifically related to discontinuing IV glucose.