Hyperosmolar hyperglycaemic state (HHS)

Hyperosmolar hyperglycaemic state (HHS) is a medical emergency that can be difficult to manage and has a significant associated mortality (up to 20%). Hyperglycaemia results in osmotic diuresis, severe dehydration, and electrolyte deficiencies. HHS typically presents in the elderly with type 2 diabetes mellitus (T2DM).

Pathophysiology

• hyperglycaemia → ↑ serum osmolality → osmotic diuresis → severe volume depletion

Precipitating factors

• intercurrent illness
• dementia
• sedative drugs

Clinical features

• whilst DKA presents within hours of onset, HHS comes on over many days, and consequently, the dehydration and metabolic disturbances may be more extreme
• consequences of volume loss
  • clinical signs of dehydration
  • polyuria
  • polydipsia
• systemic
  • lethargy
  • nausea and vomiting
• neurological
  • altered level of consciousness
  • focal neurological deficits
• haematological
  • hyperviscosity (may result in myocardial infarctions, stroke and peripheral arterial thrombosis)

There are no precise

diagnostic criteria

but the following are typically seen

• hypovolaemia
• marked hyperglycaemia (>30 mmol/L)
• significantly raised serum osmolarity (> 320 mosmol/kg)

  • can be calculated by: 2 * Na + glucose + urea