A 60-year-old man with long-standing type 2 diabetes presents in hyperosmolar hyperglycaemic state with glucose 780 mg/dL, serum sodium 148 mEq/L, and effective serum osmolality 338 mOsm/kg. Ketones are trace positive and pH is 7.38. Compared with diabetic ketoacidosis, which statement about this condition is CORRECT?
- A Total body potassium deficit is usually smaller than in DKA
- B Fluid deficit typically exceeds 20% of total body water ✓
- C Insulin requirement is higher, mandating fixed high-dose infusion rates
- D Cerebral oedema is more frequent than in DKA
Correct answer: B. Fluid deficit typically exceeds 20% of total body water
Explanation
Hyperosmolar hyperglycaemic state evolves over days, and profound osmotic diuresis produces water deficits around 20 to 25% of body weight, roughly double the typical DKA deficit of 10 to 15%. Total body potassium depletion is similar or greater, requiring careful repletion. Low dose insulin regimens used in HHS mirror those of DKA, so higher fixed doses are not required. Cerebral oedema is rare in adult HHS and is chiefly a paediatric DKA complication.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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