What are the key differences in managing Diabetic Ketoacidosis (DKA) versus Hyperosmolar Hyperglycemic State (HHS)?

Management Differences Between DKA and HHS

The key difference in managing Diabetic Ketoacidosis (DKA) versus Hyperosmolar Hyperglycemic State (HHS) is that fluid replacement is the cornerstone of HHS therapy, while insulin therapy is the cornerstone of DKA management, with HHS requiring more cautious correction of osmolality (3-8 mOsm/kg/h) to prevent neurological complications. 1, 2

Diagnostic Criteria Differences

• DKA:

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

• HHS:

  • Blood glucose typically ≥600 mg/dL
  • Serum osmolality >320 mOsm/kg
  • Absence of significant ketosis
  • Profound dehydration 1, 2

Initial Management Approach

Fluid Therapy

• DKA:

  • Isotonic saline (0.9% NaCl) at 15-20 mL/kg/h initially
  • Goal to correct estimated fluid deficit (typically ~6 liters) within 24 hours 1

• HHS:

  • More aggressive initial fluid replacement due to more severe dehydration
  • Careful monitoring of serum osmolality with target reduction of 3-8 mOsm/kg/h
  • Fluid replacement alone will cause significant blood glucose reduction 2

Insulin Therapy

• DKA:

  • Start immediately after excluding hypokalemia
  • IV bolus of regular insulin at 0.15 U/kg followed by continuous infusion at 0.1 U/kg/h 1

• HHS:

  • Consider withholding insulin until blood glucose stops falling with IV fluids alone
  • Early insulin use before adequate fluid resuscitation may be detrimental in HHS 2
  • Lower insulin doses may be required compared to DKA 3

Electrolyte Management

• Both conditions:

  • Potassium replacement is critical (20-30 mEq/L when K+ <5.3 mEq/L)
  • Use 2/3 KCl and 1/3 KPO₄ for replacement 1

• DKA-specific:

  • Bicarbonate therapy only recommended when arterial pH <6.9
  • No bicarbonate when pH ≥7.0 1

• HHS-specific:

  • Initial rise in sodium is expected and not an indication for hypotonic fluids
  • More careful monitoring of osmolality changes to prevent neurological complications 2

Monitoring Parameters

• DKA:

  • Resolution criteria: glucose <200 mg/dL, bicarbonate ≥18 mEq/L, venous pH >7.3 1
  • Focus on resolving ketoacidosis

• HHS:

  • Monitor serum osmolality regularly
  • More gradual correction of hyperosmolarity to prevent central pontine myelinolysis
  • Higher risk of thrombotic complications requiring vigilance 2

Complications and Mortality

• DKA:

  • Mortality rate: 3.4-4.6%
  • Risk of cerebral edema, particularly in younger patients 4

• HHS:

  • Higher mortality rate: approximately 15%
  • Higher risk of myocardial infarction, stroke, seizures, and central pontine myelinolysis 2, 4

Common Pitfalls to Avoid

1. In DKA:

   • Premature discontinuation of IV insulin before resolving ketosis
   • Inadequate potassium replacement
   • Unnecessary bicarbonate administration 3

2. In HHS:

   • Too rapid correction of hyperosmolality
   • Starting insulin before adequate fluid resuscitation
   • Underestimating fluid deficit 2

3. In both conditions:

   • Failure to identify and treat precipitating causes
   • Insufficient transition planning to subcutaneous insulin
   • Inadequate monitoring of electrolytes 1, 3

Special Considerations

• Approximately one-third of patients may present with mixed features of both DKA and HHS, requiring a tailored approach based on predominant features 5

• Patients with cardiovascular disease require cardiac monitoring during treatment 1

• ICU admission is indicated for patients with cardiovascular instability, airway concerns, obtundation, or acute abdominal signs 5

• Diabetes specialist team involvement should be sought as early as possible, especially in HHS management 2