A client is admitted with diabetic ketoacidosis (DKA). What is the nurse's priority intervention?

Diabetic ketoacidosis is an acute metabolic crisis driven by severe insulin deficiency, presenting with profound hyperglycemia and a massive osmotic diuresis. This uncontrolled urinary excretion drains intravascular reserves, causing up to 10 percent total body fluid deficit and hypovolemic shock. Prioritizing intravenous rehydration restores systemic tissue perfusion, dilutes circulating counter-regulatory hormones, and stabilizes the glomerular filtration rate. A. Administer insulin immediately: Administering insulin before restoring intravascular volume can cause a rapid extracellular-to-intracellular fluid shift, worsening vascular collapse. Intravenous volume expansion must always be initiated prior to or alongside insulin to secure hemodynamic stability. Premature standalone insulin usage accelerates hypovolemic shock. B. Give oral glucose: The clinical presentation of this crisis involves extreme plasma glucose elevations exceeding 13.9 mmol/L, rendering additional carbohydrates dangerous. Furthermore, severe dehydration and potential altered consciousness introduce high risks for aspiration pneumonia. Supplying oral sugars is completely contraindicated in hyperglycemic emergencies. C. Start IV fluids: Infusing large volumes of 0.9 percent sodium chloride expands the depleted intravascular compartment and counteracts profound cellular dehydration. This mechanical fluid restoration immediately reduces serum glucose through dilution while preserving critical renal perfusion. It stands as the absolute primary therapeutic priority. D. Restrict fluids: Limiting fluid intake in a severely volume-depleted, diuretic state accelerates vascular collapse, tissue ischemia, and terminal renal failure. The body requires aggressive fluid resuscitation to survive the massive ongoing solute-driven water losses. Restricting fluid intake is lethal in this condition.