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Hyperosmolar hyperglycaemic state
Hyperosmolar hyperglycaemic state

Hyperosmolar hyperglycaemic state

Hyperosmolar hyperglycaemic state (HHS) occurs in type 2 diabetes mellitus. It is a medical emergency, comprising <1% of all diabetes-related admissions, however, the mortality rate is high (5%-15%) and it is extremely difficult to manage.

It was previously referred to as hyperglycaemic hyperosmolar non-ketotic coma (HONK) as type 2 diabetics produce insulin and therefore allow glucose to enter cells which mitigates the production of ketones.

It is may seem similar to DKA but in T2DM, however, there are some clear differences:

DKA
HHS
Onset
Hours - day
Days - week
Affected group
T1DM
T2DM
Criteria
Hyperglycaemia, ketoacidosis
Hyperglycaemia, no ketones.
🤔
What characterises HHS?

It is characterised by

  • Severe hyperglycaemia - >30mmol/L
  • Hyperosmolality - >320mmol/kg
  • Volume depletion - presenting with hypotension.
  • Absence of ketoacidosis - pH >7.35 and bicarbonate >15mmol/L

Pathophysiology

HHS is precipitated by infection, hydration disturbances, electrolyte imbalances:

  1. Hyperglycaemia leads to osmotic diuresis.
  2. Continued osmotic diuresis → hypernatraemia (especially in the elderly with compromised renal function or inability to hydrate sufficiently)
  3. Hypernatraemia + hyperglycaemia + inadequate hydration + osmotic diuresis → profound hypovolaemia.
  4. Hypovolaemia leads to a progressive decline in the glomerular filtration rate → further worsening the hyperglycaemic state.
  5. Infection further aggravates this by release of counter-regulatory hormones such as glucagon, cortisol, adrenaline which induce ketogenesis, insulin resistance and further worsens the hyperglycaemia.
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⚠️ Risk factors and causes

  • Infection - as infection increases metabolic demand and increases hormones such as cortisol, glucagon and adrenaline which counter-regulate insulin. It is the major precipitating factor, occurring in 30%-60% of cases.
  • Medications - such as diuretics (excessive fluid loss can lead to hyperglycaemia and hyperosmolality). Atypical antipsychotics may also lower glucose tolerance.
  • Surgery - similarly increases metabolic demands.
  • Impaired renal function - affects serum osmolality and glycaemic levels.
  • Stroke and other CVS incidents - as these also cause a stress response.

😷 Presentation

General symptoms include:

  • Nausea and vomiting
  • Lethargy
  • Weakness
🫀
Cardiovascular symptoms:
  1. Tachycardia
  2. Dehydration
  3. Hypotension
🩸
Haematological symptoms:
  • Hyperviscosity of blood which can lead to MI, stroke and peripheral arterial thrombosis.
🧠
Neurological symptoms:

Acute cognitive impairment - a GCS or AVPU is to be done. It can range in its severity, for example:

  1. Altered consciousness
  2. Confusion
  3. Headaches
  4. Coma
  5. Seizure

This is due to cerebral oedema, electrolyte disturbances, osmolality changes, dehydration, sepsis, hypoglycaemia, renal failure.

🔍 Investigations

🌬️
Laboratory investigations:
  1. Blood glucose
    1. Hyperglycaemia (>30.0mmol/L)
  2. Blood ketones
    1. Low (<3.0 mmol/L)
  3. Venous blood gas (VBG)
    1. Mild acidosis but pH >7.3
    2. Bicarbonate >15mmol/L
  4. Serum osmolality
    1. High (>320mmol/kg)
  5. U&Es
    1. Hyponatraemia - dilutional hyponatraemia
  6. FBC
    1. Leukocytosis - infection may precipitate DKA.
  7. ECG
    1. Assessing for CVS effects/causes such as MI.

🧰 Management

With HHS our aims are to treat the underlying cause, while simultaneously also:

  • Replacing fluids and electrolytes
  • Normalising osmolality
  • Normalising blood glucose
💧
Fluid resuscitation:
  • 0.9% NaCl will gradually decrease blood glucose and osmolality.

The regimen is the same as the JBDS regimen for DKA.

JBDS example of fluid regimen

Fluid
Volume
0.9% NaCl 1L
1000ml over 1st hour
0.9% NaCl 1L + potassium chloride
1000ml over next 2 hours (500ml per hour)
0.9% NaCl 1L + potassium chloride
1000ml over next 2 hours (500ml per hour)
0.9% NaCl 1L + potassium chloride
1000ml over next 4 hours (250ml per hour)
0.9% NaCl 1L + potassium chloride
1000ml over next 4 hours (250ml per hour)
0.9% NaCl 1L + potassium chloride
1000ml over next 6 hours (167ml per hour)

JBDS potassium guidelines

Potassium level in first 24 hours
Potassium replacement in mmol/L of infusion replacement
>5.5
0
3.5-5.5
40mmol/L
<3.5
Senior review needed as additional potassium to be given.
💉
Insulin:

Insulin may be given at 0.05 units/kg/hour IF:

  1. IV fluids have been given already. If not it may cause CVS collapse as water leaves the intravascular space very rapidly.
  2. Ketones >1mmol/L or glucose fails to fall with IV fluids

Similar to with DKA, a long acting insulin will be continued afterwards.

🩸
VTE prophylaxis:

VTE prophylaxis such as LMWH to be given due to hyperviscosity.