Which lab finding is most characteristic of diabetic ketoacidosis?

• A. Anion gap metabolic acidosis with elevated ketones and low bicarbonate
• B. Hyperchloremic metabolic acidosis without ketones
• C. Metabolic alkalosis with ketones
• D. Normal acid-base with high bicarbonate

Answer: (A)

In diabetic ketoacidosis the body cannot use insulin effectively, so fat breakdown increases and ketone bodies (acetoacetate and beta-hydroxybutyrate) accumulate. These ketones are acidic, so they raise the anion gap and consume bicarbonate as the body buffers the excess hydrogen ions. The result is an anion gap metabolic acidosis with elevated ketones and a low bicarbonate level. This ketotic, high-anion-gap acidosis is the hallmark of DKA, distinguishing it from conditions with metabolic acidosis without ketosis or from metabolic alkalosis or normal-acid-base states.