Treatment of Hyperosmolar Hyperglycemic State
The cornerstone of HHS treatment is aggressive intravenous fluid resuscitation with 0.9% sodium chloride as the primary intervention, with insulin therapy deliberately delayed until osmolality stops declining with fluids alone (unless significant ketonaemia is present), aiming for gradual osmolality reduction of 3-8 mOsm/kg/h to prevent catastrophic neurological complications. 1, 2
Diagnostic Criteria
Before initiating treatment, confirm HHS diagnosis with the following parameters:
- Serum osmolality ≥320 mOsm/kg (calculated as [2×Na+] + glucose + urea) 1
- Marked hyperglycemia ≥30 mmol/L (≥540 mg/dL) 1
- Absence of significant ketosis (β-hydroxybutyrate ≤3.0 mmol/L) 1
- Minimal acidosis (pH >7.3, bicarbonate ≥15 mEq/L) 1
- Neurological abnormality, most commonly altered mental status 3
Phase 1: Initial Management (0-60 minutes)
Fluid Resuscitation - The Primary Intervention
Intravenous 0.9% sodium chloride is the principal fluid for restoring circulating volume, as fluid losses typically range from 100-220 mL/kg. 1, 4
- Begin aggressive volume replacement immediately upon diagnosis 1
- Fluid replacement alone will cause blood glucose to fall - this is expected and desired 4
- Exercise caution in elderly patients who may not tolerate rapid fluid shifts 1
- An initial rise in sodium level is expected and normal; this is not an indication to switch to hypotonic fluids 4
Critical Pitfall: Insulin Timing
Withhold insulin until blood glucose stops falling with IV fluids alone, unless significant ketonaemia is present (>3.0 mmol/L). 1, 4 This represents a fundamental difference from DKA management and is crucial because:
- Early insulin use before adequate fluid resuscitation may be detrimental 4
- Fluid replacement alone effectively lowers glucose initially 4
- Premature insulin risks precipitous osmolality changes and neurological complications 1
Phase 2: Ongoing Management (1-24 hours)
Insulin Administration (When Indicated)
Once osmolality plateaus with fluids or if ketonaemia is present:
- Fixed-rate intravenous insulin infusion (FRIII) is the preferred method 1
- Regular insulin or rapid-acting insulin analogs can be used 5
- Initial bolus followed by continuous infusion 5
Glucose Management Targets
- Maintain blood glucose 10-15 mmol/L (180-270 mg/dL) in the first 24 hours 1
- Start glucose infusion (5% or 10% dextrose) once glucose falls below 14 mmol/L (252 mg/dL) 1
- In HHS specifically, maintain glucose 250-300 mg/dL until hyperosmolarity and mental status improve 6
Osmolality Monitoring - The Critical Safety Parameter
Aim for gradual osmolality reduction of 3-8 mOsm/kg/h (maximum 3 mOsm/kg/h in high-risk patients). 1, 6 This is the single most important monitoring parameter because:
- Rapid osmolality correction can cause cerebral edema 6
- Central pontine myelinolysis may occur with overly aggressive correction 4
- Measure or calculate serum osmolality every 2-4 hours 6, 1
Potassium Replacement
Monitor potassium levels closely and replace according to serum concentrations, as insulin therapy drives potassium intracellularly. 1, 5
- Careful monitoring required to prevent life-threatening hypokalemia 6
- Consider 20-30 mEq/L potassium phosphate in replacement fluids if phosphate <1.0 mg/dL and patient has cardiac dysfunction, anemia, or respiratory depression 6
Bicarbonate Therapy
Bicarbonate is generally not indicated in HHS since significant acidosis is absent by definition (pH >7.3). 1 If mixed DKA/HHS occurs with pH <6.9, bicarbonate may be considered, though evidence for benefit is limited. 6
Resolution Criteria
HHS is considered resolved when ALL of the following are achieved:
- Osmolality <300 mOsm/kg 1
- Hypovolemia corrected (urine output ≥0.5 mL/kg/h) 1
- Cognitive status returned to pre-morbid baseline 1
- Blood glucose <15 mmol/L (270 mg/dL) 1
Transition to Subcutaneous Insulin
Continue intravenous insulin for 1-2 hours after initiating subcutaneous insulin to ensure adequate plasma insulin levels and prevent rebound hyperglycemia. 6 Abrupt discontinuation of IV insulin without overlapping subcutaneous coverage leads to poor glycemic control. 6
Critical Care Considerations
- Admit to intensive care unit - these patients are critically ill with high mortality 3
- Nurse in areas where staff are experienced in HHS management 4
- Involve diabetes specialist team immediately 4
- Identify and treat underlying precipitants (most commonly infection, but also stroke, acute coronary syndrome) 7, 2
- Implement VTE prophylaxis, prevent foot ulceration, and monitor for fluid overload 1
Key Differences from DKA Management
The most critical distinction is that HHS develops over days (not hours), causing more extreme dehydration and metabolic disturbances. 4 This necessitates: