DKA treatment is more than closing the anion gap. It is controlled correction of a severe metabolic and osmotic disturbance.
In DKA, insulin deficiency and counter-regulatory hormone excess drive hyperglycemia, ketogenesis, osmotic diuresis, dehydration, electrolyte loss, and metabolic acidosis. The brain adapts to the hyperosmolar environment. When osmolality changes too quickly, water shifts can become dangerous.
Cerebral edema is uncommon in adults but devastating when it occurs. It is more common in children, but the physiology matters across age groups. Several factors may contribute: severe acidosis, high urea nitrogen, hypocapnia, rapid osmotic shifts, and underlying severity of illness. Treatment must respect the physiology.