What is the insulin drip protocol for patients with Diabetic Ketoacidosis (DKA)?

Insulin Drip Protocol for Diabetic Ketoacidosis (DKA)

For patients with DKA, the recommended insulin protocol is an initial IV bolus of regular insulin at 0.15 U/kg body weight, followed by a continuous infusion at 0.1 U/kg/hour (approximately 5-7 U/hour in adults). 1

Initial Assessment and Classification

DKA is defined by:

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

Severity classification:

Parameter	Mild	Moderate	Severe
Arterial pH	7.25-7.30	7.00-7.24	<7.00
Bicarbonate (mEq/L)	15-18	10-14	<10
Mental Status	Alert	Alert/drowsy	Stupor/coma

Step-by-Step Insulin Protocol

1. Initial Fluid Resuscitation

   • Begin with isotonic saline (0.9% NaCl) at 15-20 ml/kg/hour to expand intravascular volume 1
   • Aim to correct estimated fluid deficits (typically ~6 liters) within 24 hours

2. Insulin Administration

   • Ensure potassium is >3.3 mEq/L before starting insulin
   • Administer IV bolus of regular insulin at 0.15 U/kg body weight
   • Follow with continuous IV infusion at 0.1 U/kg/hour 1
   • Continue insulin infusion until DKA resolves (not just until glucose normalizes)

3. Glucose Management

   • For mild DKA: Target glucose between 150-200 mg/dL until resolution
   • For moderate/severe DKA: Target glucose between 150-200 mg/dL until resolution
   • For HHS: Target glucose between 200-250 mg/dL until resolution 2
   • When glucose falls below 200-250 mg/dL, add dextrose to IV fluids while continuing insulin infusion

4. Potassium Replacement

   • Add potassium to IV fluids when serum levels fall below 5.5 mEq/L (with confirmed adequate urine output)
   • Standard replacement: 20-30 mEq potassium per liter of IV fluid (2/3 KCl and 1/3 KPO₄) 1
   • If K+ <3.3 mEq/L, hold insulin and give potassium replacement first

5. Monitoring

   • Hourly: Vital signs, neurological status, blood glucose, fluid input/output
   • Every 2-4 hours: Electrolytes, BUN, creatinine, venous pH, osmolality 1

Resolution Criteria

DKA is considered resolved when:

• Blood glucose <200 mg/dL
• Serum bicarbonate ≥18 mEq/L
• Venous pH >7.3
• Anion gap normalized (<12 mEq/L) 1

Transition to Subcutaneous Insulin

1. When DKA is resolved and patient can eat:

   • Initiate subcutaneous multi-dose insulin plan
   • Continue IV insulin infusion for 1-2 hours after first subcutaneous dose to prevent rebound hyperglycemia 2

2. For established diabetes patients:

   • Resume previous regimen with adjustments as needed
   • Consider reducing total daily dose by 20% if previously requiring >0.6 U/kg/day 1

Important Considerations and Pitfalls

• Avoid hypoglycemia: When glucose falls below 200-250 mg/dL, add dextrose to IV fluids but continue insulin infusion until acidosis resolves
• Bicarbonate therapy: Only consider when arterial pH is below 6.9; not recommended when pH is 7.0 or higher 1
• Cerebral edema risk: More cautious fluid administration in pediatric patients (≤20 years)
• Phosphate replacement: Not routinely recommended unless there is muscle weakness or respiratory compromise 1
• Avoid premature discontinuation: Continue insulin infusion until DKA resolution criteria are met, not just until normoglycemia

Special Populations

• Pediatric patients: Use 1.5 times the 24-hour maintenance requirement for fluid administration (approximately 5 ml/kg/hr) 1
• Pregnant patients: Be vigilant for euglycemic DKA, which requires immediate attention 1
• Cardiac patients: Implement cardiac monitoring during treatment 1

The evidence strongly supports that this protocol is effective in resolving DKA while minimizing complications such as hypoglycemia and hypokalemia. While some research has explored alternative approaches like subcutaneous insulin analogs for mild-moderate DKA 3, 4, the continuous IV insulin infusion remains the standard of care recommended by current guidelines, particularly for moderate to severe cases.