A patient with diabetic ketoacidosis has a blood pH of 7.2, a bicarbonate level of 10 mEq/L, and a PCO2 of 30 mmHg. What is the most likely cause of the acid-base disturbance in this patient?

The patient's blood pH is acidic, and the bicarbonate level is low, indicating a metabolic acidosis. The low PCO2 suggests that there is also a respiratory component, as the patient is hyperventilating to compensate for the metabolic acidosis.