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

Comparison of DKA vs HHS Management and Treatment

The management of DKA and HHS differs primarily in fluid replacement needs, insulin dosing approach, and resolution criteria, with HHS requiring more aggressive fluid resuscitation due to greater dehydration (9L vs 6L deficit), while DKA treatment focuses on resolving ketoacidosis even after glucose normalizes. 1

Diagnostic Criteria Differences

• DKA is characterized by blood glucose >250 mg/dL, arterial pH <7.3, bicarbonate <15 mEq/L, and moderate ketonuria or ketonemia 1
• HHS is characterized by blood glucose >600 mg/dL, arterial pH >7.3, bicarbonate >15 mEq/L, effective serum osmolality >320 mOsm/kg, and altered mental status or severe dehydration 1, 2
• Mixed states with features of both conditions occur in approximately one-third of patients, requiring a tailored therapeutic approach 3

Fluid Therapy Differences

• HHS requires more aggressive fluid replacement due to greater dehydration (total body water deficit ~9 liters or 100-200 mL/kg) compared to DKA (total body water deficit ~6 liters) 1, 4
• Both conditions initially require isotonic saline (0.9% NaCl) at 15-20 mL/kg/h during the first hour 4, 2
• In HHS, fluid replacement alone may initially manage glucose decline, with insulin therapy delayed until after initial fluid resuscitation 5
• For both conditions, fluid replacement should correct estimated deficits within 24 hours, with induced change in serum osmolality not exceeding 3 mOsm/kg/h 2

Insulin Therapy Differences

• In DKA, insulin therapy should be initiated immediately with an IV bolus of regular insulin at 0.1-0.15 units/kg body weight, followed by continuous infusion at 0.1 unit/kg/h 1, 6
• In DKA, insulin should be continued until resolution of ketoacidosis (pH >7.3, serum bicarbonate ≥18 mEq/L, and anion gap ≤12 mEq/L) even if blood glucose normalizes 1, 6
• In HHS, insulin dosing may be lower (starting at 0.1 units/kg/h without bolus) after ensuring adequate fluid resuscitation and potassium levels 2, 5
• For both conditions, if plasma glucose does not fall by 50 mg/dL in the first hour, double the insulin infusion hourly until achieving steady glucose decline of 50-75 mg/h 2, 6

Electrolyte Management Differences

• Potassium deficits are typically greater in HHS (5-15 mEq/kg) compared to DKA (3-5 mEq/kg) 4, 1
• For both conditions, begin potassium replacement after serum levels fall below 5.5 mEq/L, assuming adequate urine output 6
• Add 20-40 mEq potassium per liter of infusion fluid to maintain serum potassium between 4-5 mEq/L 2, 6
• Phosphate replacement (20-30 mEq/L potassium phosphate) should be considered only in patients with cardiac dysfunction, anemia, respiratory depression, or serum phosphate <1.0 mg/dL 2, 6

Bicarbonate Therapy

• Bicarbonate administration is generally not recommended in either condition 2, 6
• For DKA patients with pH <6.9, consider administering 100 mmol sodium bicarbonate in 400 mL sterile water at 200 mL/h 6
• For DKA patients with pH 6.9-7.0, consider administering 50 mmol sodium bicarbonate in 200 mL sterile water at 200 mL/h 6

Monitoring Differences

• In DKA, direct measurement of β-hydroxybutyrate in blood is the preferred method for monitoring ketone resolution 1, 6
• Both conditions require monitoring of serum electrolytes, glucose, blood urea nitrogen, creatinine every 2-4 hours 1, 2
• In HHS, careful monitoring of mental status and serum osmolality is crucial 2

Resolution Criteria Differences

• DKA resolution requires: glucose <200 mg/dL, serum bicarbonate ≥18 mEq/L, venous pH >7.3, and anion gap ≤12 mEq/L 1, 6
• HHS resolution requires: normalized osmolality, improved mental status, and glucose <300 mg/dL 2

Transition to Subcutaneous Insulin

• For both conditions, basal insulin should be administered 2-4 hours before stopping IV insulin to prevent rebound hyperglycemia 4, 1
• Recent studies show that low-dose basal insulin analog given with IV insulin may prevent rebound hyperglycemia in both conditions 4, 1
• When transitioning to subcutaneous insulin, use a combination of short/rapid-acting and intermediate/long-acting insulin 6

Complications and Pitfalls

• In DKA: Premature termination of insulin therapy before complete resolution of ketosis can lead to recurrence 1, 7
• In HHS: Overly rapid correction of hyperosmolality can lead to cerebral edema 2, 5
• In both conditions: Inadequate fluid resuscitation and electrolyte replacement can worsen outcomes 1, 7
• Monitoring for cerebral edema signs is crucial, especially in younger patients 2, 6
• Common complications in HHS include renal failure, respiratory distress, rhabdomyolysis, heart failure, hypercoagulation, hyperthermia, arrhythmias, and pancreatitis 5

Treatment Algorithm Summary

1. Initial assessment: Confirm diagnosis based on glucose, pH, bicarbonate, ketones, and osmolality 4, 1
2. Fluid therapy: Begin with isotonic saline at 15-20 mL/kg/h, more aggressive in HHS 1, 2
3. Insulin therapy: Start IV insulin immediately in DKA; may delay in HHS until after initial fluid resuscitation 1, 5
4. Electrolyte management: Monitor and replace potassium when <5.5 mEq/L 2, 6
5. Monitor: Check electrolytes, glucose, BUN, creatinine every 2-4 hours 1, 2
6. Transition: Administer basal insulin 2-4 hours before stopping IV insulin 4, 1
7. Identify and treat precipitating causes (infection, medication non-compliance, etc.) 4, 2