What are the treatment differences between Hyperosmolar Hyperglycemic State (HHS) and Diabetic Ketoacidosis (DKA)?

Treatment Differences Between HHS and DKA

The primary treatment difference between Hyperosmolar Hyperglycemic State (HHS) and Diabetic Ketoacidosis (DKA) is that fluid replacement is the cornerstone of HHS therapy, while insulin therapy is the cornerstone of DKA management, though both conditions require a three-pronged approach of fluid administration, insulin therapy, and electrolyte replacement. 1

Key Differences in Presentation and Pathophysiology

DKA

• Develops rapidly (hours to days, typically <24h) 2
• Characterized by:
  • Blood glucose >250 mg/dL
  • Arterial pH <7.3
  • Serum bicarbonate <15 mEq/L
  • Moderate ketonemia or ketonuria 2
• Presents with Kussmaul respirations (deep, rapid breathing) 2
• Abdominal pain is characteristic of DKA but not HHS 2
• Insulin deficiency and ketoacidosis are prominent features 1

HHS

• Evolves more slowly (several days to weeks) 2
• Characterized by:
  • Marked hyperglycemia (often >600 mg/dL)
  • Hyperosmolality
  • Little or no ketosis 3
• More severe dehydration than DKA 3
• Higher mortality rate (approximately 15% vs 3.4-4.6% for DKA) 3
• Residual beta-cell function adequate to prevent lipolysis but not hyperglycemia 3

Treatment Approach

Fluid Replacement

• HHS: More aggressive fluid replacement is the cornerstone of therapy 1

  • Patients have more severe dehydration
  • Higher risk of vascular occlusion if undertreated

• DKA: Fluid replacement is important but balanced with insulin therapy 2

  • Replace 50% of estimated fluid deficit in first 8-12 hours 2
  • More cautious in younger patients to avoid cerebral edema 1

Insulin Therapy

• DKA: Insulin is the cornerstone of therapy 1

  • Required to resolve ketoacidosis
  • Continue until resolution of ketonemia 4

• HHS: Insulin is needed but may be less urgent than fluid replacement 1

  • Less aggressive insulin therapy may be appropriate

Target Glucose Levels

• DKA: Keep glucose between 150-200 mg/dL until resolution 2
• HHS: Keep glucose between 200-250 mg/dL until resolution 2

Electrolyte Replacement

• Both conditions require careful monitoring and replacement of electrolytes, particularly potassium 2, 4
• Potassium levels must be monitored as hypokalemia may occur during treatment 2

Resolution Criteria

• DKA: Considered resolved when:

  • Glucose <200 mg/dL
  • Serum bicarbonate ≥18 mEq/L
  • Venous pH >7.3 2

• HHS: Resolution primarily focuses on correcting hyperosmolality and dehydration 1

Monitoring Requirements

• Hourly monitoring for both conditions:

  • Vital signs
  • Neurological status
  • Blood glucose
  • Fluid input/output 2

• Every 2-4 hours:

  • Electrolytes
  • BUN
  • Creatinine
  • Venous pH 2

Common Pitfalls to Avoid

1. Premature discontinuation of IV insulin therapy before resolution of metabolic abnormalities 4
2. Insufficient timing or dosing of subcutaneous insulin before discontinuing IV insulin 4
3. Overly rapid correction of metabolic abnormalities in younger patients, which can precipitate cerebral edema 1
4. Inadequate fluid replacement in HHS, which can lead to vascular occlusion 1
5. Failure to identify and treat the precipitating cause 4
6. Inadequate monitoring of electrolytes, particularly potassium 2

Transition to Subcutaneous Insulin

For both conditions:

• Administer subcutaneous basal insulin 2-4 hours before discontinuing IV insulin to prevent rebound hyperglycemia 2
• Check blood glucose 2 hours after IV insulin discontinuation 2
• Continue frequent monitoring (every 3-4 hours) for the first 24 hours after transition 2

Special Considerations

• Mixed cases with features of both DKA and HHS occur in up to one-third of patients 1
• In adult patients with mixed features, fluids may be administered more rapidly than in younger patients 1
• Patients presenting with DKA may have type 1 diabetes requiring life-long insulin therapy 1
• ICU admission is indicated for both conditions when there is cardiovascular instability, airway concerns, obtundation, or acute abdominal signs 1