A diabetic in ketoacidosis breathes deep and fast (Kussmaul breathing). Ketone acids drop blood pH; the lungs compensate within minutes by blowing off CO2 (deep rapid breathing) to raise pH, while kidneys take hours–days to excrete acid and regenerate bicarbonate. The fruity breath odor is acetone. Treatment addresses the cause (insulin, fluids) — the breathing is compensation, not the disease, and suppressing it would be fatal.