A man with diabetic ketoacidosis has glucose 28 mmol/L, pH 7.1 and serum potassium 3.0 mmol/L before any treatment. What should be done first?

Answer and explanation

Correct answer: C. Give potassium replacement and delay the insulin infusion until potassium is above 3.3 mmol/L

  1. Step 1: Total body potassium is depleted in ketoacidosis, and the measured value is already low. Step 2. Insulin moves potassium into cells, so starting it with a level below 3.3 mmol/L can cause fatal hypokalaemic arrhythmia. Answer: Replace potassium first and hold insulin until it is above 3.3 mmol/L. Why not the others: Immediate insulin would drop the potassium further. Bicarbonate is not routine at pH 7.1 and also lowers potassium. Dextrose is added only when glucose falls, and the patient is hyperglycaemic now.

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