Which acid-base disturbance is characteristic of diabetic ketoacidosis?

• A. Non-anion gap metabolic acidosis
• B. Anion gap metabolic acidosis
• C. Metabolic alkalosis
• D. Respiratory alkalosis

Answer: (B)

In diabetic ketoacidosis, the problem is an anion gap metabolic acidosis. When insulin is deficient, the body increases lipolysis and ketogenesis, leading to a buildup of ketoacids (primarily beta-hydroxybutyrate and acetoacetate) in the blood. These unmeasured anions are buffered by bicarbonate, which is consumed in the process, causing the bicarbonate level to fall and the anion gap Na − (Cl + HCO3) to rise. The result is a high anion gap metabolic acidosis. The body often compensates with rapid, deep breathing (Kussmaul respiration) to blow off CO2. Other acid-base disturbances don’t fit this classic pattern: a non-anion gap acidosis would come from bicarbonate loss with preserved anion balance; metabolic alkalosis is the opposite disturbance; and respiratory alkalosis reflects excessive CO2 loss rather than ketone accumulation.