A 42-year-old woman with type 2 diabetes mellitus presents with nausea, vomiting, and rapid shallow breathing for 2 days. She admits to poor medication adherence. On examination, she is alert, respiratory rate 32/min, and breath has a fruity odor. Arterial blood gas: pH 7.18, PaCO₂ 28 mmHg, HCO₃⁻ 10 mEq/L, PaO₂ 98 mmHg. Blood glucose 480 mg/dL, serum ketones positive. What is the primary acid-base disorder and the appropriate respiratory response?