Dose Conversion from Lantus to Tresiba
Convert unit-to-unit (1:1 ratio) when switching from Lantus (insulin glargine) to Tresiba (insulin degludec), maintaining the same total daily basal insulin dose. 1
Standard Conversion Approach
The recommended conversion is a direct 1:1 unit-to-unit switch - if a patient is taking 30 units of Lantus daily, start 30 units of Tresiba daily. 1 This straightforward approach is supported by clinical practice guidelines for switching between basal insulin formulations.
Key Differences to Understand
While the dose conversion is 1:1, Tresiba has distinct pharmacological properties that affect clinical management:
- Tresiba has an ultra-long duration of action (>42 hours) compared to Lantus (approximately 24 hours), which means steady-state concentrations are not reached for 2-3 days after initiation or dose changes. 1
- Wait at least 1 week before making subsequent dose adjustments after switching to Tresiba to fully assess glucose outcomes, rather than the 3-day intervals used with Lantus. 2
Monitoring During Transition
- Check fasting blood glucose daily during the first 1-2 weeks after switching to identify any need for dose adjustment. 2
- Monitor for hypoglycemia closely, particularly if the patient was experiencing frequent hypoglycemia on Lantus, as Tresiba's longer duration may provide more stable coverage with potentially lower hypoglycemia risk. 1
- If hypoglycemia occurs without clear cause, reduce the dose by 10-20% immediately. 3, 2
Titration After Conversion
Once steady state is achieved (after approximately 1 week):
- Increase by 2 units every 3-7 days if fasting glucose is 140-179 mg/dL. 2
- Increase by 4 units every 3-7 days if fasting glucose is ≥180 mg/dL. 2
- Target fasting plasma glucose of 80-130 mg/dL. 3, 2
Critical Threshold Recognition
- When basal insulin exceeds 0.5 units/kg/day and approaches 1.0 units/kg/day, add prandial insulin rather than continuing to escalate basal insulin alone to avoid overbasalization. 3, 2
- Clinical signals of overbasalization include: bedtime-to-morning glucose differential ≥50 mg/dL, hypoglycemia, and high glucose variability. 2
Common Pitfalls to Avoid
- Do not reduce the dose prophylactically when converting from Lantus to Tresiba unless the patient has frequent hypoglycemia on Lantus - use the same total daily dose. 1
- Do not make dose adjustments within the first week after switching, as Tresiba requires time to reach steady state. 2
- Continue metformin unless contraindicated when switching basal insulins. 3, 2