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HHS — RACP Adult Medicine MCQ

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ModerateEndocrinologyHHSRACP Adult Medicine

A 75-year-old man with type 2 diabetes presents with profound dehydration, confusion, and a blood glucose of 48 mmol/L. Venous pH is 7.35, bicarbonate 22 mmol/L, serum ketones 1.0 mmol/L. Calculated serum osmolality is 365 mOsm/kg. What is the most likely diagnosis?

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Correct answer: D — Hyperosmolar hyperglycaemic state

HHS is characterised by severe hyperglycaemia (>30 mmol/L), hyperosmolality (>320 mOsm/kg), and dehydration without significant ketoacidosis (pH >7.3, bicarbonate >15). It carries higher mortality than DKA. Management priorities are cautious fluid resuscitation (0.9% NaCl) and low-dose insulin. Fluid replacement must be gradual to prevent cerebral oedema.

Reference: Australian Diabetes Society – 2024 – HHS Guidelines