Transitioning from Insulin IV Infusion to Subcutaneous Insulin
When transitioning from IV insulin infusion to subcutaneous insulin, administer subcutaneous basal insulin 2 hours before discontinuing the IV insulin infusion and use 50-60% of the 24-hour IV insulin requirement as the total daily subcutaneous insulin dose, with half given as basal insulin and half divided into prandial doses. 1
When to Transition
- Transition when:
Calculating Subcutaneous Insulin Doses
Step 1: Calculate Total Daily Insulin (TDI)
- Calculate based on IV insulin requirements during the previous 6-8 hours when glucose was stable 1
- Multiply the hourly rate by 24 to get the 24-hour requirement
- Use 50-60% of this 24-hour requirement as the starting TDI 2, 1, 3
Step 2: Distribute the TDI
- Give 50% as basal insulin (long-acting)
- Divide the remaining 50% into three equal doses of rapid-acting insulin for meals 2, 1
Step 3: Timing of Administration
- Administer the first dose of basal insulin 2 hours before discontinuing the IV insulin infusion 1
- This overlap prevents rebound hyperglycemia
Example Calculation
For a patient receiving IV insulin at 2 units/hour:
- 24-hour insulin requirement = 2 units/hour × 24 hours = 48 units
- TDI = 50-60% of 48 units = 24-29 units
- Basal insulin = 12-14.5 units
- Prandial insulin = 4-5 units per meal (3 meals)
Insulin Regimen Selection
Basal-Bolus Regimen (Preferred)
- Most physiologic approach that best replicates normal pancreatic function 2
- Consists of:
- Basal insulin: Long-acting insulin (glargine, detemir) once or twice daily
- Bolus insulin: Rapid-acting insulin before meals
- Correction doses: Additional rapid-acting insulin for hyperglycemia 2
Avoid Sliding Scale Insulin Alone
- Sliding scale insulin alone (without basal insulin) is associated with poor glycemic control and is not recommended 2, 1
- Exception: Patients without diabetes who have mild stress hyperglycemia 2
Special Considerations
Type 1 Diabetes
- Must always include basal insulin in the regimen
- Never use sliding scale insulin alone 2
- Resume previous treatment combining basal and bolus insulin at adjusted doses based on hospital requirements 2
Type 2 Diabetes
- For patients previously on oral medications only:
- Consider continuing basal-bolus insulin if HbA1c >9% or blood glucose remains >11 mmol/L (2 g/L)
- Consider transitioning back to oral medications if renal function permits (clearance >30 mL/min for most agents, >60 mL/min for metformin) 2
Renal Insufficiency
- Consider lower insulin doses due to decreased insulin clearance 1
Monitoring After Transition
- Check blood glucose before meals and at bedtime
- Monitor more frequently (every 4-6 hours) during the first 24 hours after transition
- Target glucose range: 140-180 mg/dL for most hospitalized patients 2, 1
Hypoglycemia Management
- Implement a hypoglycemia management protocol
- For blood glucose <70 mg/dL (3.9 mmol/L): Treat with 15-20g of fast-acting carbohydrate
- For blood glucose <60 mg/dL (3.3 mmol/L): Administer glucose immediately even without symptoms 1
- For unconscious patients: Use IV glucose 1
Common Pitfalls and How to Avoid Them
- Rebound hyperglycemia: Ensure 2-hour overlap between basal insulin and IV insulin discontinuation
- Hypoglycemia: Start with 50-60% of IV requirements rather than 80-100% 3, 4
- Inadequate monitoring: Check glucose every 4-6 hours for the first 24 hours after transition
- Failure to adjust for nutritional status: Reduce prandial insulin if oral intake is poor
- Medication errors: Use standardized protocols and dedicated infusion lines for insulin 1
By following this structured approach to transitioning from IV to subcutaneous insulin, you can maintain glycemic control while minimizing the risks of both hyperglycemia and hypoglycemia, ultimately improving patient outcomes.