Hyperosmolar hyperglycaemic state (HHS)

Objectives

Safely manage HHS on Ops

Scope

How do I manage the patient with very high blood glucose level (>30 mmol/L / 540 mg/dL) AND hypovolaemia AND osmolality of 320 mmol/L or higher?

Audience

Trained HCPs

Initial Assessment & Management

You may prefer the HHS algorithm designed to print on a single side of A4, here

Non-UK glucose unit conversion

mmol/L

mg/dL

3.9

70

7.0

126

11.0

198

If Systolic BP 90 or less or evidence of shock, give rapid resuscitation e.g. 500ml fluid challenge (box E)

 

Check ketones and blood gas. pH <7.3 or bicarb <15mmol/L AND ketosis (dipstick '++' or greater; capillary ketones >3 mmol/L) - Use Diabetic Ketoacidosis (DKA)

 

Calculate osmolality (2 × (Na+K) + Urea + Glucose)

320mOsm/kg or more?

YES - Diagnosis is HHS. This is a medical emergency. Consider HDU care. Document treatment goals.

 

Give 1 litre 0.9% saline over 1 h (slower if heart failure a concern)

Advanced Assessment & Management

If capillary ketones > 1 or Urine ketones ++ or greater, commence IV insulin 0.05 Units/kg per hour. Add 10% dextrose 100ml/h when BG less than 14mmol/l

Document estimated fluid losses - approx. 110-220 ml/kg depending on severity of dehydration, chronicity etc. 

  • If osmolality falling 3-8mOsm/kg per h, give 500-1000ml/h to achieve treatment goal 1 (box A)
  • If osmolality falling over 8mOsm/kg per h, consider reducing rate IV fluids or reducing insulin infusion rate (if commenced)
  • If osmolality falling by less than 3 mOsm/kg per h, increase rate of fluids aiming to achieve treatment goal 1 (Box A). If adequate fluid resuscitation has been achieved, change to 0.45% saline.

Potassium replacement

  • If K 3.5 - 5.5 add 40mmol KCl per litre of fluid
  • If K <3.5, needs faster replacement (max 20mmol/h)
  • If K <3.5 or >5.5 needs consideration for HDU: seek senior advice

Prolonged Casualty Care

Ongoing management of HHS is intensive. Consider referring to next role at earliest opportunity

 

Principle of management : Give IV fluids until BG stops falling; when BG static (i.e. falling <2mmol/L per h) add in IV insulin

Regularly reassess and seek early specialist support via reachback

Every hour you need to:

  • Monitor hourly input/ output (urinary catheter required)
  • Review observations
  • Check capillary blood glucose

Every 2 hours you need to:

  • Check UEs & venous glucose (Expect increase in Na)
  • Chart osmolality and glucose (overleaf) – see 'blood glucose falling < 2mmol/L per h' if relevant
  • Document clinical/biochemical progress
  • Assess for fluid overload
  • Assess for cerebral oedema
  • Commence prophylactic anticoagulation

Reduce the above to 6-8 hourly after 6 hours of treatment

Continue IV fluids until eating and drinking normally

Needs urgent escalation to next role for HDU care if 1 of:

  • Osmolality greater than 350mosm/kg
  • Na greater than 160mmol/L
  • H+ 80 or greater
  • K less than 3.5 or greater than 5.5 on admission
  • O2 sats less than 92% on air
  • Systolic BP less than 90mmHg
  • GCS less than 12
  • Heart rate less than 60 or greater than 100
  • Urine OP less than 0.5ml/kg/h after initial resuscitation
  • Hypothermia
  • Other serious comorbidity
  • Creatinine greater than 200μmol/L
  • MI, stroke or other macrovascular event

Treatment goals

1.Replace fluid and electrolyte loss - 2-3 L positive fluid balance by 6 hours and 3-6 L positive fluid balance within 12 hours; restore 100% estimated losses (see box B) by 24 hours

2.Normalise glucose gradually over 12-24h reduction no more than 5mmol/L per hour. Target 10 – 15 mmol/L. Fluids should achieve most of this.

3.Target decline in osmolality of 3-8 mOsm/kg per h

4.Prevent complications (cerebral oedema, arterial/venous thrombosis, foot ulceration); check for pressure ulcers daily

5.Identify and treat underlying cause (e.g. sepsis)

Blood Glucose falling less than 2 mmol/L per h

Is fluid management achieving treatment goal 1? (See box A)

  • No – increase ate of fluids aiming to achieve treatment goal 1.

Adequate rehydration will reduce blood glucose. Without fluid resuscitation IV insulin can cause circulatory collapse.

  • Yes – commence low dose IV insulin (0.05 units/kg per hour)

      -   Aim blood glucose reduction up to 5 mmol/L per hour.

      -   Target blood glucose is 0 – 15 mmol/L

      -   Add 10% dextrose 100 ml/h when glucose less than 14mmol/L

HHS algorithm for a single side of A4

Monitoring chart for patients with HHS (print-out)

 

Last reviewed: 16/02/2026

Next review date: 16/02/2027

References

Joint British Diabetes Societies guideline JBDS06: The management of the hyperosmolar hyperglycaemic state (HHS) in adults with diabetes | The Association of British Clinical Diabetologists