Final answer:
Parents of a child with diabetes insipidus should watch for confusion and disorientation as signs of water intoxication, which can occur due to an electrolyte imbalance.
Step-by-step explanation:
Diabetes insipidus is a condition marked by polyuria (frequent urination) and polydipsia (increased thirst). When educating parents of a child with diabetes insipidus on water intoxication, the nurse would advise them to be alert for symptoms such as confusion and disorientation, which are the result of an electrolyte imbalance due to excessive water intake. Swelling of the extremities is not typically associated with water intoxication but rather with other medical conditions.