Last Modified: 3:18pm 15/04/2021

How to recognise HHS

Hyperosmolar Hyperglycaemic State (HHS) occurs in people with Type 2 diabetes who experience very high blood glucose levels (often over 40mmol/l). It can develop over a course of weeks through a combination of illness (e.g.infection) and dehydration.

Hyperosmolar hyperglycaemic state (HHS) has no precise definition, but characteristic features that differentiate it from other hyperglycaemic states such as Diabetic ketoacidosis (DKA) are

  • Hypovolaemia
  • Marked hyperglycaemia (30mmol/L or more) without significant hyperketonaemia (< 3mmol/L),
    ketonuria (2+ or less) or acidosis (pH>7.3, bicarbonate> 15mmol/L).
  • Osmolality usually 320mosmol/kg or more.

N.B. A mixed picture of HHS and DKA may occur. Metabolic acidosis may be present in patients who are critically unwell.

HHS symptoms can frequently include:

  • urination,
  • thirst
  • nausea
  • dry skin
  • disorientation and, in later stages, drowsiness and a gradual loss of consciousness.

Hospital treatment for HHS aims to  treat the underlying cause and to gradually and safely: 

  • Normalise the osmolality
  • Replace fluid and electrolyte losses
  • Normalise blood glucose.

Other goals include prevention of:

  • Arterial or venous thrombosis
  • Other potential complications e.g. cerebral oedema/central pontine myelinolysis
  • Foot ulceration

Resolution of HHS occurs when there is complete normalisation of electrolytes and osmolality, this may take up to 72 hours.