IV Insulin Administration: Dilution and Infusion Rate
For IV insulin infusion, prepare regular human insulin at a standardized concentration of 1 unit/mL in 0.9% normal saline, prime the tubing with 20 mL waste volume, and infuse at 0.1 units/kg/hour for DKA or 0.5-1 unit/hour for general critical care hyperglycemia. 1
Preparation Protocol
Use only regular human insulin (Humulin R U-100 or equivalent) for all continuous IV infusions, as it is the only appropriate formulation for IV administration with predictable pharmacokinetics 1, 2
Standardized concentration is 1 unit/mL prepared in 0.9% normal saline using polyvinyl chloride infusion bags 1, 2
Prime the IV tubing with 20 mL of the insulin solution as waste before connecting to the patient to saturate binding sites in the tubing 1
Use dedicated IV tubing for insulin infusions to avoid compatibility issues and ensure accurate dosing 1
Dosing and Infusion Rates
For Diabetic Ketoacidosis (DKA):
Initial rate: 0.1 units/kg/hour as continuous infusion after confirming serum potassium >3.3 mEq/L 3, 1
- An optional initial bolus of 0.15 units/kg may be given in adults (not recommended in pediatrics) 3
Target glucose decline of 50-75 mg/dL per hour 3
- If glucose does not fall by 50 mg/dL in the first hour, check hydration status and double the insulin infusion rate hourly until achieving steady decline 3
When glucose reaches 250 mg/dL, add 5% dextrose to IV fluids (0.45-0.75% NaCl) while continuing insulin infusion 3, 4
- Maintain glucose between 150-200 mg/dL until complete DKA resolution (pH >7.3, bicarbonate ≥18 mEq/L) 4
For General Critical Care Hyperglycemia:
Initial rate: 0.5-1 unit/hour with titration based on hourly glucose monitoring 1
Adjust infusion rate using multipliers based on rate of glucose change to prevent both persistent hyperglycemia and hypoglycemia 5
Monitoring Requirements
Check blood glucose every 1-2 hours during active titration, then every 2-4 hours once stable 3, 4
Monitor serum potassium closely during insulin infusion, as insulin causes intracellular potassium shift and can precipitate life-threatening hypokalemia 3, 2
Check electrolytes, renal function, venous pH, and osmolality every 2-4 hours until stable 4
Critical Safety Considerations
Inspect insulin vials immediately before use—solution must be completely clear and colorless; any cloudiness or discoloration indicates loss of potency and the vial must be discarded 1, 2
Never stop IV insulin abruptly without administering subcutaneous basal insulin first 6, 4
Do not mix other medications with insulin in the same solution unless specifically approved by pharmacy 1
Hypoglycemia prevention: If glucose drops below 70 mg/dL, administer 10-20 grams IV dextrose (D50) and recheck in 15 minutes 6
- Most hypoglycemic events occur due to measurement delays (66.9% of cases), so ensure timely glucose checks 7
Storage and Stability
Unopened vials: Store refrigerated at 2-8°C (36-46°F); do not freeze 2
In-use vials: Can remain unrefrigerated below 30°C (86°F) for up to 31 days 2
Prepared infusion bags: Stable refrigerated for 48 hours, then may be used at room temperature for an additional 48 hours 2
Common Pitfalls to Avoid
Failing to add dextrose when glucose falls below 250 mg/dL during DKA treatment while continuing insulin—this is essential because ketonemia takes longer to clear than hyperglycemia 3, 4
Interrupting insulin infusion when glucose normalizes—this is a common cause of persistent or worsening ketoacidosis 4
Using rapid-acting or long-acting insulin analogs IV—only regular human insulin should be used for IV administration 1
Inadequate tubing priming—insulin binds to IV tubing, so 20 mL waste volume is necessary for accurate dosing 1