A 24-year-old man with type 1 diabetes presents with vomiting, Kussmaul breathing, glucose 520 mg/dL, pH 7.08, bicarbonate 6 mEq/L, and serum potassium 3.0 mEq/L. Insulin infusion is planned. What must be done FIRST regarding potassium?

• A Start insulin infusion immediately and add potassium simultaneously
• B Hold all fluids until potassium normalises
• C Start sodium bicarbonate infusion before any potassium
• D Give 20 to 30 mEq of potassium per litre of fluid and delay insulin until serum potassium exceeds 3.3 mEq/L ✓

Explanation

Insulin drives potassium into cells and can precipitate fatal hypokalaemia when the admission value is already low. Standard DKA protocols hold insulin until serum potassium is above 3.3 mEq/L while giving potassium in the fluids. Bicarbonate is reserved for pH below 6.9 and does not address the potassium risk, which is the immediate danger here.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.