Synopsis
Recognise adult hyperosmolar hyperglycaemic state, restore volume gradually, track osmolality and introduce insulin only at the correct physiological stage.
- Typical HHS combines marked hypovolaemia with glucose at least 30 mmol/L, calculated osmolality at least 320 mOsm/kg, minimal ketonaemia and no substantial ketoacidosis, but the whole syndrome matters more than one threshold.
- Calculate osmolality using the JBDS expression 2 × sodium + glucose + urea, with all components in mmol/L, and plot it against glucose, sodium and fluid balance.
- Correct gradually: the usual osmolality target is a fall of 3–8 mOsm/kg/hour and glucose should not fall faster than 5 mmol/L/hour.
Key red flags
Several days of thirst, polyuria, weakness, weight loss and declining intake may progress to severe dehydration, tachycardia, hypotension and oliguria.
Investigation priorities
Confirm the hyperosmolar syndrome and quantify the hourly rate of physiological correction.
Management branches
An adult has extreme hyperglycaemia, dehydration, cognitive change or a prolonged osmotic prodrome.
- Perform ABCDE and obtain bedside glucose, blood ketones, venous gas, sodium, potassium, urea and creatinine, then calculate and record osmolality immediately.
- Assess volume, consciousness, oxygenation, urine output, comorbidity and thrombosis while searching for infection, vascular events and medicines that precipitated deterioration.
Key medicines
Intravenous 0.9% sodium chlorideUse the staged volumes and rates on the current adult JBDS HHS chart, modified after each clinical and osmolality review for shock, age, heart failure, renal impairment and the measured fluid response.
Fixed-rate intravenous insulin for HHSWhen glucose has ceased falling after adequate fluid, use 0.05 units/kg/hour under the JBDS HHS protocol; use 0.1 units/kg/hour only for specified mixed DKA/HHS with significant ketonaemia and acidosis.