Which electrolyte disturbance is a concern when starting insulin in DKA even if the initial potassium is normal?

• A. Hyperkalemia
• B. Hypokalemia
• C. Hyponatremia
• D. Hypercalcemia

Answer: (B)

Initiating insulin in DKA can cause potassium to fall even if potassium looks normal at presentation. This happens because insulin stimulates the Na+/K+-ATPase pump, driving potassium from the extracellular space into cells. As the insulin infusion corrects the acidosis and the hyperglycemia resolves, the shift of potassium into cells accelerates, exposing a hidden total-body potassium deficit created by osmotic diuresis and losses in vomiting or poor intake. So, even with a normal initial potassium, starting insulin can lead to a clinically important drop in serum potassium, i.e., hypokalemia.

That’s why potassium management is intertwined with insulin therapy in DKA. If the potassium is above a safe threshold, you start insulin but must replace potassium to keep serum levels in the target range, typically around 4–5 mEq/L. If potassium is below the threshold, you delay insulin and correct potassium first. Hyponatremia and hypercalcemia aren’t the primary concerns driven by insulin initiation in this context, though sodium shifts related to glucose correction can occur.