How do you mix regular insulin (Novolin) for diabetic ketoacidosis (DKA)?

Mixing Regular Insulin for Diabetic Ketoacidosis (DKA)

For DKA treatment, regular insulin should be administered as an intravenous (IV) infusion at 0.1 units/kg/hour without an initial bolus dose. 1

Preparation of IV Insulin Infusion

1. Select the correct insulin:

   • Use regular insulin (Humulin R or Novolin R)
   • Ensure the insulin solution is clear and colorless 2

2. Prepare the infusion:

   • Calculate the dose based on patient weight (0.1 units/kg/hour)
   • For a typical adult, this translates to approximately 7-8 units/hour 1
   • Use proper syringe marked for U-100 insulin preparations 2

3. Mixing technique:

   • Draw regular insulin from vial using aseptic technique
   • Add to IV solution according to hospital protocol
   • No bolus dose is needed when initiating therapy 1

Administration and Monitoring

1. Initial administration:

   • Start IV insulin infusion at 0.1 units/kg/hour
   • Administer concurrently with appropriate fluid resuscitation (0.9% NaCl at 15-20 ml/kg/hour for the first hour) 1

2. Monitoring requirements:

   • Check blood glucose hourly until stable
   • Monitor electrolytes, renal function, and venous pH every 2-4 hours
   • Target glucose level of 150-200 mg/dL for DKA 1

3. Adjustments:

   • When blood glucose falls below 200 mg/dL, add dextrose to IV fluids
   • Continue insulin infusion until DKA resolves (glucose <200 mg/dL, serum bicarbonate ≥18 mEq/L, and venous pH >7.3) 1

Transitioning from IV to Subcutaneous Insulin

1. Timing:

   • Administer subcutaneous basal insulin 2-4 hours before discontinuing IV insulin infusion 1, 3
   • This overlap prevents rebound hyperglycemia and recurrence of ketoacidosis

2. Dosing considerations:

   • Do not rely solely on correction insulin without basal insulin 1
   • Calculate appropriate subcutaneous insulin doses based on patient's insulin requirements during IV therapy

Important Considerations and Pitfalls

• Avoid abrupt discontinuation of IV insulin without proper transition to subcutaneous insulin to prevent rebound hyperglycemia 1

• Fluid management is as critical as insulin therapy in DKA management 1

• Electrolyte monitoring is essential, particularly potassium, as insulin therapy can cause hypokalemia 1

• For severe DKA cases, higher insulin doses (up to 14 units/hour) may occasionally be required with appropriate glucose infusion to prevent hypoglycemia, though standard dosing (0.1 units/kg/hour) is typically sufficient 4

• Cerebral edema risk should be considered, especially in younger patients, by avoiding too rapid correction of serum osmolality 1

By following these guidelines for mixing and administering regular insulin for DKA, you can effectively manage this potentially life-threatening condition while minimizing complications.