Diabetic ketoacidosis presenting with a normal anion gap

Historically, diabetic ketoacidosis has been attributed exclusively to the accumulation of ketoacids resulting in wide anion gap metabolic acidosis. An unusual patient with non-insulin-dependent diabetes mellitus who presented with mild hyperglycemia, ketonemia, and acidosis with a normal anion gap is described. No other known causes of hyperchloremic metabolic acidosis were present, and resolution of acidosis followed administration of intravenous insulin. This case illustrates that the finding of a normal anion gap, per se, may not exclude the presence of diabetic ketoacidosis.