# A 19-year-old client with type 1 diabetes is 4 hours into treatment for diabetic ketoacidosis with IV 0.9% sodium chloride, a continuous regular insulin infusion, and potassium added to the maintenance fluid. Admission values: glucose 612 mg/dL, pH 7.08, bicarbonate 7 mEq/L, potassium 4.6 mEq/L. Current values: glucose 380 mg/dL, pH 7.28, bicarbonate 14 mEq/L, potassium 3.1 mEq/L, sodium 132 mEq/L, effective osmolality 285 mOsm/kg. The client is drowsy but easily aroused and oriented, with a Glasgow Coma Scale score of 14, unchanged since admission; the client denies headache, and pupils are equal and reactive. Heart rate is 88/min, blood pressure 110/70 mm Hg, and respirations 26/min and deep. The cardiac monitor shows new flattened T waves. Urine output has been 30 mL/hr for 2 hours. Complete the diagram by selecting the condition the client is most likely experiencing, 2 actions the nurse should take to address that condition, and 2 parameters the nurse should monitor to assess the client's progress.

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> subject: Medical Emergencies  
> category: PA

## Question

A 19-year-old client with type 1 diabetes is 4 hours into treatment for diabetic ketoacidosis with IV 0.9% sodium chloride, a continuous regular insulin infusion, and potassium added to the maintenance fluid. Admission values: glucose 612 mg/dL, pH 7.08, bicarbonate 7 mEq/L, potassium 4.6 mEq/L. Current values: glucose 380 mg/dL, pH 7.28, bicarbonate 14 mEq/L, potassium 3.1 mEq/L, sodium 132 mEq/L, effective osmolality 285 mOsm/kg. The client is drowsy but easily aroused and oriented, with a Glasgow Coma Scale score of 14, unchanged since admission; the client denies headache, and pupils are equal and reactive. Heart rate is 88/min, blood pressure 110/70 mm Hg, and respirations 26/min and deep. The cardiac monitor shows new flattened T waves. Urine output has been 30 mL/hr for 2 hours. Complete the diagram by selecting the condition the client is most likely experiencing, 2 actions the nurse should take to address that condition, and 2 parameters the nurse should monitor to assess the client's progress.

Condition

Select 1
Cerebral edema from a rapid osmolar shift during treatment
Hyperosmolar hyperglycemic state
Persistent ketoacidosis from too little insulin
Hypokalemia from insulin-driven potassium shift

Actions to take

Select 2
Prepare 3% saline for the client's drowsiness
Hold the insulin infusion per protocol
Give sodium bicarbonate for the pH of 7.28
Infuse IV potassium chloride as prescribed
Increase the insulin rate to close the anion gap

Parameters to monitor

Select 2
Serum osmolality every 4 hours
Neurologic checks with pupil response
Serum potassium every 1 to 2 hours
Urine specific gravity each void
Cardiac rhythm on continuous ECG

## Explanation

Insulin and correction of acidosis drive potassium into cells, and this client's potassium has fallen to 3.1 mEq/L with ECG changes, the most immediate treatment complication. The nurse holds the insulin infusion per protocol until potassium is at least 3.5 mEq/L and infuses IV potassium as prescribed. Serum potassium every 1 to 2 hours and continuous cardiac rhythm show whether replacement is working.

## In-depth explanation

Quick answer
Hypokalemia from insulin-driven potassium shift; hold insulin per protocol and infuse IV potassium as prescribed; monitor serum potassium every 1 to 2 hours and the continuous ECG rhythm.

Why this is correct
Glucose, pH, and bicarbonate are all moving in the right direction, so the ketoacidosis is responding to therapy. Potassium, however, has dropped from 4.6 to 3.1 mEq/L and flattened T waves have appeared. Consensus guidance directs potassium replacement and holding insulin when potassium falls below 3.5 mEq/L, because further insulin would push potassium even lower and risk dysrhythmias and respiratory muscle weakness.

Easy analogy or mental picture
Insulin is a doorman that ushers potassium from the bloodstream into the cells. When the hallway is almost empty, close the door for a moment and refill the hallway before letting the doorman work again.

Memory hook
"Under 3.5 — potassium in, insulin paused."

NCLEX decision rule
In a DKA client on an insulin infusion, a potassium below 3.5 mEq/L outranks the glucose number: replace potassium and pause insulin, then monitor potassium and cardiac rhythm closely.

Why the other choices are wrong
Hypertonic saline treats cerebral edema, but this client's level of consciousness is unchanged and oriented, with no headache or pupil change. Bicarbonate is not indicated at pH 7.28, and increasing insulin would worsen hypokalemia even though the anion gap is still open. HHS is excluded by an effective osmolality of 285 mOsm/kg (2 x 132 + 380/18) with marked ketoacidosis, and persistent ketoacidosis is contradicted by the steadily improving pH and bicarbonate. Serum osmolality and urine specific gravity are less specific, and neurologic checks track the cerebral-edema differential rather than the potassium problem.

References
1ADA Consensus Report — Hyperglycemic Crises in Adults With Diabetes (2024)During DKA treatment, potassium below 3.5 mmol/L requires potassium replacement with insulin delayed or held until potassium is restored, plus frequent electrolyte checks.

## Clinical scenario

Scenario
Four hours into DKA treatment, acidosis and glucose are improving, but potassium has fallen from 4.6 to 3.1 mEq/L and the monitor shows new flattened T waves.

## Key concepts

- **Transcellular potassium shift** — Movement of potassium from the blood into cells, driven by insulin and correction of acidosis.
- **Effective osmolality** — Calculated as 2 x sodium + glucose/18; values above 320 mOsm/kg suggest hyperosmolar hyperglycemic state.
- **Flattened T wave** — An ECG change that commonly accompanies low serum potassium.

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