Final answer:
Fluid volume deficient is a high-priority nursing diagnosis for both diabetic ketoacidosis and hyperosmolar hyperglycemic syndrome.
Step-by-step explanation:
A high-priority nursing diagnosis for both diabetic ketoacidosis and hyperosmolar hyperglycemic syndrome is Fluid volume deficient.
In both conditions, the body experiences excessive fluid loss due to increased urination and dehydration. This can lead to hypovolemia, electrolyte imbalances, and impaired tissue perfusion. Therefore, monitoring and managing fluid volume is an important nursing priority.