In type 1 diabetes, what effect does insulin have on potassium distribution?

• A. Insulin promotes potassium uptake into cells, lowering serum potassium.
• B. Insulin promotes potassium release from cells.
• C. Insulin does not affect potassium.
• D. Insulin increases renal potassium excretion.

Answer: (A)

Insulin drives potassium into cells by activating the Na+/K+-ATPase pump, which pulls K+ from the extracellular space into the intracellular compartment and lowers serum potassium. In type 1 diabetes, lack of insulin means less cellular uptake of potassium, so extracellular potassium can be higher even though total body potassium may be depleted. When insulin is given to treat hyperglycemia and acidosis, it promotes a rapid shift of potassium into cells, causing serum potassium to fall and sometimes leading to hypokalemia if not monitored. The idea that insulin releases potassium from cells is incorrect, and insulin’s primary effect here isn’t increasing renal potassium excretion or having no effect at all.