🚨 Hyperosmolar Hyperglycaemic State
Overview
Hyperosmolar Hyperglycaemic State (HHS), previously known as HONK, is a severe, life-threatening complication of type 2 diabetes, characterised by extreme hyperglycaemia, hyperosmolarity, and dehydration, without significant ketosis or acidosis. It typically affects older individuals and has a high mortality rate.
Recognition
Patients present with profound dehydration, altered mental status (ranging from confusion to coma), and often a history of polyuria and polydipsia over several days or weeks. Focal neurological deficits or seizures can occur. There is typically no Kussmaul breathing or 'pear drop' breath odour.
Initial Assessment (ABCDE)
A: Assess airway patency; protect if GCS is low. B: Assess breathing for rate and oxygen saturation. C: Assess circulation for heart rate, blood pressure, capillary refill, and signs of severe dehydration/shock. D: Assess disability using GCS, and check blood glucose. E: Expose fully to check for signs of infection, skin turgor, and temperature.
Red Flags
Profound dehydration with signs of hypovolaemic shock, rapidly decreasing GCS, seizures, focal neurological deficits, and severe electrolyte imbalances (especially hypernatraemia or rapidly changing sodium) are critical red flags. Any signs of cardiovascular collapse or respiratory compromise are also concerning.
Investigations
Bedside: Capillary blood glucose, urine dipstick (minimal or no ketones), ECG. Bloods: Arterial or venous blood gas (for pH, bicarbonate, pCO2), urea and electrolytes, creatinine, calculated serum osmolality, full blood count, blood cultures if infection suspected. Imaging: Chest X-ray if respiratory symptoms, CT head if neurological deficits or cerebral oedema suspected.
Immediate Management
Administer high-flow oxygen if hypoxic. Establish intravenous access and commence aggressive intravenous fluid resuscitation with isotonic saline, carefully monitoring fluid balance. Start a low-dose intravenous insulin infusion once rehydration has begun and potassium levels are adequate. Monitor and replace electrolytes, particularly potassium and sodium, cautiously. Identify and treat any precipitating factors.
Escalation Triggers
Any patient presenting with HHS requires immediate senior medical review. Deterioration in GCS, signs of severe shock, persistent neurological deficits, or severe electrolyte abnormalities warrant urgent critical care involvement. Failure to improve despite initial management also requires escalation.
MLA High-Yield Notes
HHS is distinct from DKA by the absence of significant ketosis and acidosis, but with much higher glucose levels and profound dehydration/hyperosmolarity. Fluid replacement is the cornerstone of treatment, often requiring large volumes. Rapid correction of hypernatraemia can lead to cerebral oedema, so fluid management must be careful. Often triggered by infection or poor compliance.
References
- Joint British Diabetes Societies (JBDS) for Inpatient Care: Management of Hyperosmolar Hyperglycaemic State (HHS) in Adults
- NICE Guideline NG18: Diabetes (type 1 and type 2) in children and young people: diagnosis and management
- Resuscitation Council UK: Advanced Life Support Guidelines