Why does the serum potassium level increase with diabetes ketoacidosis?

High potassium. Diabetic ketoacidosis (DKA) increases potassium (K) levels due to the acidosis (A) seen in DKA. A causes K to leave the cells and go into the blood. As DKA is treated, the A resolves, increasing the pH of the blood, so K goes back into the cells lowering the blood K level.