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Hyperosmolar hyperglycaemic state — MRCEM SBA MCQ

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EasyResuscitation and critical illnessHyperosmolar hyperglycaemic stateMRCEM SBA

A 71-year-old man with type 2 diabetes is brought to the emergency department after four days of thirst, polyuria and increasing confusion. He is drowsy but rousable, with dry mucous membranes, a pulse of 106/min and blood pressure of 104/62 mmHg. Blood glucose is 40 mmol/L, sodium 147 mmol/L, urea 18 mmol/L and potassium 4.2 mmol/L. Capillary ketones are 0.3 mmol/L; venous pH is 7.37 and bicarbonate is 23 mmol/L. Intravenous access and monitoring are established, but treatment has not started. Senior review and assessment for a higher-acuity bed are being arranged. Which initial fluid and insulin strategy is most appropriate?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: C — Start 0.9% sodium chloride; begin intravenous insulin if osmolality stops falling.

The marked hyperglycaemia, dehydration and calculated osmolality of 352 mOsm/kg (2 × 147 + 40 + 18), together with minimal ketonaemia and no acidosis, indicate hyperosmolar hyperglycaemic state (HHS), rather than diabetic ketoacidosis. Begin volume replacement with 0.9% sodium chloride and monitor glucose, sodium and osmolality frequently. Fluid replacement itself lowers glucose and osmolality; in HHS without significant ketonaemia, intravenous insulin is introduced if osmolality stops falling despite fluids. His osmolality also warrants senior assessment of the appropriate level of care. ([pubmed.ncbi.nlm.nih.gov](https://pubmed.ncbi.nlm.nih.gov/36370077/?dopt=Abstract&utm_source=openai)) A starts insulin prematurely: early insulin is appropriate when significant ketonaemia accompanies HHS. B selects hypotonic saline too early; it may be considered if osmolality fails to fall despite adequate initial fluid replacement. D applies an immediate insulin strategy associated with ketoacidosis, which the blood results do not support. E mistakes 14 mmol/L for an insulin-start threshold: it is a point at which glucose-containing fluid may be needed during ongoing treatment, not the trigger for insulin in this presentation. ([nnuh.nhs.uk](https://www.nnuh.nhs.uk/publication/download/hyperosmolar-hyperglycaemic-state-hhs-in-adults-with-diabetes-quick-reference-guide-national-guidance-quick-reference))

Reference: Management of Hyperosmolar Hyperglycaemic State (HHS) in Adults: An updated guideline from the Joint British Diabetes Societies for Inpatient Care Group (March 2023) — https://pubmed.ncbi.nlm.nih.gov/36370077/ JBDS Guidance on Management of Hyperosmolar Hyperglycaemic State in Adults: Quick Reference Guide (Date not stated on document) — https://www.nnuh.nhs.uk/publication/download/hyperosmolar-hyperglycaemic-state-hhs-in-adults-with-diabetes-quick-reference-guide-national-guidance-quick-reference