Immediate Management of Hyperosmolar Hyperglycemia
Begin with aggressive isotonic saline resuscitation at 15-20 mL/kg/h in the first hour, followed by continuous IV insulin only after fluid resuscitation has begun and hypokalemia is excluded. 1, 2
Initial Assessment and Diagnosis
Obtain immediate laboratory studies to confirm HHS and guide management: 2
- Arterial blood gases (pH >7.3 distinguishes HHS from DKA) 1
- Blood glucose (typically >600 mg/dL in HHS) 2
- Serum electrolytes, BUN, creatinine, complete blood count, urinalysis 2
- Calculate effective serum osmolality using: 2[measured Na (mEq/L)] + glucose (mg/dL)/18 (typically >320 mOsm/kg in HHS) 1, 2
- Calculate corrected sodium by adding 1.6 mEq/L for each 100 mg/dL glucose above 100 mg/dL 1
Identify precipitating factors including infection, myocardial infarction, stroke, or medications (diuretics, corticosteroids, beta-blockers) 2, 3
Fluid Resuscitation (First Priority)
Start with isotonic saline (0.9% NaCl) at 15-20 mL/kg/h (approximately 1-1.5 L in average adult) during the first hour to restore intravascular volume and renal perfusion 1, 2. This is critical because fluid replacement alone will cause blood glucose to fall 4.
After initial resuscitation, adjust fluid choice based on corrected serum sodium and hemodynamic status 2. Target fluid replacement should correct estimated deficits within 24 hours 2.
Important caveat: Early use of insulin before adequate fluid resuscitation may be detrimental 4. The UK guidelines specifically recommend withholding insulin until blood glucose is no longer falling with IV fluids alone (unless ketonemic) 4.
Insulin Therapy (After Fluid Resuscitation)
Once hypokalemia is excluded (K⁺ >3.3 mEq/L), initiate continuous IV regular insulin with: 1, 2
- Loading dose: 0.15 units/kg IV bolus 1
- Continuous infusion: 0.1 units/kg/h (typically 5-10 units/hour) 2
When plasma glucose reaches 300 mg/dL: 2
- Decrease insulin infusion to 0.05-0.1 units/kg/h (3-6 units/hour)
- Add 5-10% dextrose to IV fluids to prevent hypoglycemia while continuing to treat hyperosmolarity
- Target glucose 250-300 mg/dL until hyperosmolarity resolves
Critical point: In critically ill and mentally obtunded patients with hyperosmolar hyperglycemia, continuous IV insulin is the standard of care 5.
Electrolyte Management
Potassium replacement is essential once renal function is confirmed: 2
- If K⁺ <3.3 mEq/L: Hold insulin and add potassium to IV fluids immediately 1
- If K⁺ >3.3 mEq/L: Add 20-30 mEq/L potassium (2/3 KCl and 1/3 KPO₄) to infusion 2
Monitor electrolytes every 2-4 hours during initial treatment 1, 2.
An initial rise in sodium is expected and is not itself an indication for hypotonic fluids 4. This occurs as glucose falls and water shifts from intracellular to extracellular space.
Monitoring Parameters
Monitor closely to avoid complications: 2
- Blood glucose every 1-2 hours until stable
- Serum electrolytes, BUN, creatinine, osmolality every 2-4 hours 1, 2
- Target osmolality reduction of 3-8 mOsm/kg/h 4
- Vital signs, mental status, fluid input/output hourly 2
Critical warning: Rapid changes in osmolality may precipitate central pontine myelinolysis, cerebral edema, or seizures 4, 6. Gradual correction is essential.
Transition to Subcutaneous Insulin
Administer subcutaneous basal insulin 2-4 hours before stopping IV insulin to prevent rebound hyperglycemia and recurrent crisis 5, 1, 2. This timing is critical—premature termination of IV insulin is a common management pitfall 7.
Special Considerations
Elderly patients and those with cardiac/renal compromise require more cautious fluid rates with closer monitoring 2, 8. HHS has higher mortality than DKA, particularly in elderly patients where age is the best prognostic indicator 8.
Do not use bicarbonate therapy routinely—it has not been shown to improve outcomes in HHS 5.
Involve the diabetes specialist team immediately and nurse patients in areas where staff are experienced in HHS management 4.