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

Management Differences Between DKA and HHS

The key management differences between Diabetic Ketoacidosis (DKA) and Hyperosmolar Hyperglycemic State (HHS) focus on fluid resuscitation, insulin therapy, and electrolyte management, with fluid replacement being the cornerstone of HHS treatment while insulin therapy is the cornerstone for DKA. 1

Diagnostic Criteria Comparison

DKA Diagnostic Criteria:

• Blood glucose >250 mg/dL 1
• Arterial pH <7.3 1
• Serum bicarbonate <15 mEq/L 1
• Moderate ketonuria or ketonemia 1
• Anion gap >10-12 mEq/L 1

HHS Diagnostic Criteria:

• Blood glucose >600 mg/dL 1
• Arterial pH >7.3 1
• Serum bicarbonate >15 mEq/L 1
• Minimal ketonuria or ketonemia 1
• Effective serum osmolality >320 mOsm/kg 1
• Altered mental status or severe dehydration 1

Fluid Management Differences

DKA:

• Initial fluid resuscitation with isotonic saline at 15-20 mL/kg/hr during first hour (1-1.5 L in average adult) 1
• Total water deficit typically around 6 liters 1
• Subsequent fluid choice depends on hydration status and corrected serum sodium 1

HHS:

• More aggressive fluid resuscitation is required as dehydration is more severe 2
• Total water deficit typically around 9 liters (50% greater than DKA) 1
• Fluid replacement alone will cause significant drop in blood glucose 3
• More careful monitoring of osmolality changes is required (aim for reduction of 3-8 mOsm/kg/hr) 3

Insulin Therapy Differences

DKA:

• Insulin therapy is the cornerstone of treatment 2
• Initial IV bolus of regular insulin at 0.15 units/kg followed by continuous infusion at 0.1 unit/kg/hr 1
• Continue insulin until ketoacidosis resolves (may require insulin even after glucose normalizes) 1
• Monitor β-hydroxybutyrate levels to track resolution of ketosis 1

HHS:

• Fluid replacement is the cornerstone of treatment, with insulin playing a secondary role 2
• Consider withholding insulin initially until blood glucose stops falling with IV fluids alone 3
• Early use of insulin before adequate fluid resuscitation may be detrimental 3
• Lower insulin doses may be sufficient as insulin resistance is less pronounced 4

Electrolyte Management

DKA:

• More aggressive potassium replacement often needed (typical deficit 3-5 mEq/kg) 1
• Phosphate replacement may be considered for severe hypophosphatemia 1
• Bicarbonate therapy generally not recommended unless pH <6.9 5

HHS:

• Larger potassium deficits (5-15 mEq/kg) require careful monitoring and replacement 1
• More gradual correction of sodium abnormalities to prevent central pontine myelinolysis 3
• Bicarbonate therapy rarely needed as acidosis is minimal 1

Monitoring Differences

DKA:

• Monitor venous pH and anion gap to track resolution of acidosis 1
• Direct measurement of β-hydroxybutyrate is preferred over nitroprusside method 1
• Resolution criteria: glucose <200 mg/dL, bicarbonate ≥18 mEq/L, venous pH >7.3 5

HHS:

• Monitor serum osmolality regularly (calculate: 2[measured Na] + glucose/18) 1
• Track mental status changes as indicator of improvement 1
• Resolution criteria: normalized osmolality, improved mental status, adequate hydration 3

Complications and Pitfalls

DKA:

• Cerebral edema (more common in pediatric patients) 1
• Premature discontinuation of insulin before ketosis resolves 4
• Relying on urine ketones instead of serum β-hydroxybutyrate 5

HHS:

• Higher mortality rate than DKA 2
• Increased risk of thromboembolism, myocardial infarction, and stroke 3
• Central pontine myelinolysis from rapid changes in osmolality 3
• Cerebral edema from too-rapid correction of hyperosmolar state 3

Transition to Subcutaneous Insulin

DKA:

• Transition when ketoacidosis resolves (pH >7.3, bicarbonate ≥18 mEq/L) 5
• Administer basal insulin 2-4 hours before stopping IV insulin 5

HHS:

• Transition when osmolality normalizes and mental status improves 3
• May not require long-term insulin if precipitating cause is addressed 2

Special Considerations

• Up to one-third of patients may present with mixed features of both DKA and HHS, requiring a tailored approach based on predominant features 2
• HHS typically develops over days, while DKA presents within hours 1
• HHS has a higher mortality rate and requires involvement of diabetes specialist team as soon as possible 3