Transitioning from Insulin Drip to Lantus
For a patient on an insulin drip at 4 units/hour, start Lantus at 48 units once daily (50% of the 24-hour IV insulin requirement of 96 units), administered subcutaneously 2-4 hours before discontinuing the IV insulin. 1
Calculation Method
The total subcutaneous insulin dose equals half of the IV insulin infused over 24 hours. 1
- Current IV insulin rate: 4 units/hour
- Total IV insulin over 24 hours: 4 units/hour × 24 hours = 96 units
- Total subcutaneous dose = 96 units ÷ 2 = 48 units 1
- Lantus (basal) dose = 50% of total subcutaneous dose = 24 units 1
- Remaining 50% (24 units) should be divided as prandial insulin before meals (8 units per meal if eating three meals) 1
Critical Timing Considerations
Administer the first Lantus dose 2-4 hours before discontinuing the insulin drip to ensure adequate overlap and prevent rebound hyperglycemia. 1 This overlap period is essential because Lantus requires time to reach therapeutic levels after subcutaneous administration, unlike IV insulin which has immediate offset once discontinued.
Adjusting for Patient Risk Factors
For high-risk patients (elderly >65 years, renal failure, or poor oral intake), reduce the calculated dose by 20-50% to prevent hypoglycemia. 1 In these populations, use lower starting doses of 0.1-0.25 units/kg/day. 1
For patients on high-dose home insulin (≥0.6 units/kg/day), reduce the total daily dose by 20% upon hospitalization. 1
Monitoring Requirements During Transition
Check point-of-care glucose before each meal and at bedtime for patients eating regular meals, targeting 140-180 mg/dL for non-critically ill hospitalized patients. 1 For patients with poor oral intake, check glucose every 4-6 hours. 1
Titrate basal insulin every 3 days based on fasting glucose patterns, with a target fasting glucose of 80-130 mg/dL. 1 Increase by 2 units if fasting glucose is 140-179 mg/dL, or by 4 units if fasting glucose is ≥180 mg/dL. 1
Prandial Insulin Component
The remaining 50% of the total subcutaneous dose (24 units in this case) must be given as prandial insulin divided among three meals, not as Lantus alone. 1 Scheduled basal-bolus regimens are superior to sliding scale monotherapy and prevent dangerous glucose fluctuations. 1
Use rapid-acting insulin (aspart, lispro, or glulisine) 0-15 minutes before meals for the prandial component. 1 Never give rapid-acting insulin at bedtime, as this significantly increases nocturnal hypoglycemia risk. 1
Common Pitfalls to Avoid
Never use sliding scale insulin as monotherapy after discontinuing the drip—this approach is explicitly condemned by all major diabetes guidelines and leads to dangerous glucose fluctuations. 1 The 75% of hospitalized patients who experienced hypoglycemia had no basal insulin dose adjustment before the next administration, demonstrating the danger of inadequate monitoring. 1
Never discontinue the insulin drip before the Lantus has time to reach therapeutic levels. 1 The lack of overlap creates a dangerous gap in insulin coverage that can precipitate severe hyperglycemia or diabetic ketoacidosis in insulin-dependent patients.
If the patient has decreased oral intake after transition, immediately reduce total daily insulin to 0.1-0.15 units/kg/day given primarily as basal insulin. 1 Continue basal insulin coverage even with minimal intake rather than relying solely on correction doses. 1