Hyperosmolar Hyperglycaemic State (HHS)Emergency

Elderly type 2 diabetes, 1 week of polyuria then confusion; very dry; glucose 980 mg/dL, Na⁺ 148, effective osmolality 345 mOsm/kg, pH 7.34, BOHB 1.1 mmol/L

• Osmolality >350 mOsm/kg
• Seizures, focal deficit, GCS <12
• Oliguria despite fluids
• Chest pain or ECG change (MI as precipitant)
• Limb ischaemia or DVT

• DKA or mixed DKA–HHS
• Stroke, meningitis, encephalitis (confusion)
• Hypernatraemic dehydration without diabetes
• Sepsis with stress hyperglycaemia

• Admit: All HHS
• ICU/HDU: Osmolality >350, Na⁺ >160, GCS <12, hypotension, hypothermia, AKI, severe comorbidity (JBDS)

• HHS carries higher mortality than DKA — older patients with comorbidities; mortality is from the precipitant, thrombosis and over-rapid correction.
• Fluid alone brings glucose down; insulin is added only when that stops (or if ketotic).
• Watch osmolality, not just glucose — plot it every 2 hours for the first 6 hours.

• Start insulin at 0.1 U/kg/h before fluids have been given — glucose and osmolality crash, fluid shifts intracellularly
• Drop Na⁺ by >10 mmol/L in 24 h
• Use hypotonic fluid as the first fluid
• Forget VTE prophylaxis and heel protection

• Treating it like DKA with high-dose insulin
• Correcting Na⁺ or osmolality too fast
• Missing the precipitant
• No thromboprophylaxis

HDU for severity markers; otherwise ward with hourly monitoring for the first 24 h. Diabetes team before discharge; insulin often needed temporarily.