Situation: A 76-year-old woman with type 2 diabetes mellitus is brought from home after three days of increasing drowsiness and poor oral intake during a febrile illness. She weighs 60 kg. The provider diagnoses hyperosmolar hyperglycemic state (HHS). Her blood pressure is 92/50 mmHg, heart rate 118 beats/min, and serum potassium 4.6 mEq/L (normal 3.5–5.0 mEq/L). She has no history of heart or kidney failure. Which order should the nurse carry out FIRST?

The first priority in HHS is fluid replacement, because severe dehydration is the main problem and fluids alone lower glucose. Insulin is started after fluids are running and potassium is confirmed adequate; starting insulin in a dehydrated client can worsen hypotension as glucose and water move into cells.

Why fluid replacement comes first in HHS

In hyperosmolar hyperglycemic state (HHS), the dominant pathophysiologic problem is profound intracellular and extracellular dehydration driven by sustained osmotic diuresis. The serum glucose rises high enough to overwhelm renal reabsorption, so glucose spills into the urine and drags water and electrolytes with it. Over several days, total body water deficits in HHS typically reach 100–200 mL/kg, which for this 60 kg patient represents roughly 6–12 L of fluid loss. This explains the hypotension (92/50 mmHg) and reflex tachycardia (118 beats/min) on presentation.

Restoring intravascular volume is the first and most urgent intervention because it improves tissue perfusion, supports blood pressure, and begins lowering serum glucose even before insulin is given. Fluid resuscitation alone reduces glucose through dilution and by improving renal perfusion, which enhances urinary glucose excretion. The initial fluid of choice is isotonic 0.9% sodium chloride, infused to expand the extracellular compartment and stabilize hemodynamics ^[1][2][3].

Watch out! Starting insulin before adequate fluid resuscitation can worsen hypotension. Insulin drives glucose and water from the extracellular space into cells, which may further reduce circulating volume in an already dehydrated patient. The consensus approach is to begin fluids first, confirm adequate blood pressure and urine output, and verify that serum potassium is not low before starting insulin ^[1][2].

Why the other options are not first

Order	Why it is not the first action	When it becomes appropriate
Regular insulin infusion	Insulin given before volume restoration can precipitate or worsen circulatory collapse by shifting glucose and water into cells; also, insulin lowers potassium and may unmask hypokalemia	After fluids are running and serum potassium is confirmed at or above 3.3 mEq/L; often started once blood pressure and urine output are adequate [1][2]
Potassium chloride in IV fluid	This patient’s potassium is 4.6 mEq/L, which is within normal range; adding potassium now is unnecessary and risks hyperkalemia	Only if potassium falls below 3.3 mEq/L or if insulin therapy causes potassium to drop; potassium is replaced once urine output is confirmed [1][3]
Sodium bicarbonate IV push	Bicarbonate is not indicated in HHS unless there is severe acidosis with pH below 6.9; HHS typically has only mild or no acidosis because enough insulin remains to suppress significant ketogenesis	Reserved for rare cases of severe metabolic acidosis or life-threatening hyperkalemia; routine use is not recommended [3]

How the potassium value guides sequencing

The serum potassium of 4.6 mEq/L is deceptively reassuring. In HHS, total body potassium is usually depleted because osmotic diuresis causes large urinary potassium losses. However, the serum level may appear normal or even high at presentation because insulin deficiency and hyperosmolality shift potassium out of cells into the extracellular fluid ^[1][2].

Once insulin is started, potassium moves back into cells, and the serum potassium can fall rapidly. This is why potassium status must be assessed before insulin administration, but it does not make potassium replacement the first priority in this patient. The immediate threat is hypovolemic shock from dehydration, not hypokalemia. With a current potassium of 4.6 mEq/L and no ECG evidence of hypokalemia, the correct sequence is fluid first, then reassess potassium before insulin ^[1][3].

Key point! The order of priorities in HHS is: (1) restore intravascular volume with isotonic saline, (2) correct electrolyte deficits once urine output is established, and (3) begin insulin only after fluids are running and potassium is confirmed adequate. This sequence prevents both worsening shock from premature insulin and dangerous hypokalemia during insulin therapy ^[1][2][3].

Clinical application to this patient

This older adult with type 2 diabetes developed HHS during a febrile illness, which increased insensible fluid losses and reduced oral intake. The three-day history of drowsiness reflects progressive hyperosmolality causing neurologic depression. The hypotension and tachycardia indicate significant volume depletion requiring immediate intervention.

The nurse should first initiate the ordered 0.9% sodium chloride infusion, typically at an initial rate guided by hemodynamic status and the degree of dehydration. For a patient with hypotension, rapid infusion of isotonic saline is appropriate to restore perfusion. Monitoring includes hourly urine output, blood pressure, heart rate, and frequent glucose and electrolyte checks. Once the patient is hemodynamically stable and potassium is confirmed adequate, insulin therapy can be added according to protocol ^[1][2].