Converting Lantus 30 Units Twice Daily to Tresiba
Convert Lantus (insulin glargine) 30 units twice daily (total 60 units/day) to Tresiba (insulin degludec) 48 units once daily, which represents 80% of the total daily Lantus dose.
Conversion Rationale
The FDA label for Lantus provides explicit guidance for this exact scenario. When transferring patients from twice-daily NPH or basal insulin to once-daily basal insulin, use 80% of the total daily dose to reduce hypoglycemia risk 1. This same principle applies when converting from twice-daily Lantus to once-daily Tresiba.
Calculation
- Current total daily dose: 30 units × 2 = 60 units
- Tresiba starting dose: 60 units × 0.80 = 48 units once daily
Why This Approach Minimizes Risk
The 20% dose reduction is critical because:
- Tresiba has a longer half-life (>42 hours) compared to Lantus (~24 hours), creating more sustained insulin exposure
- Steady-state takes 2-3 days with Tresiba, meaning insulin accumulates initially
- The FDA explicitly recommends this reduction "to lower the likelihood of hypoglycemia" 1
- Research confirms patients switching from twice-daily glargine to degludec typically require 69-78% of their original basal dose at 6 months 2
Timing and Monitoring
Administer Tresiba at the same time daily (can be any time, but consistency is key). Close glucose monitoring is essential during the first week:
- Check fasting glucose daily
- Monitor for hypoglycemia, especially during days 2-4 when steady-state is reached
- If hypoglycemia occurs without clear cause, reduce dose by 10-20% 3
- Titrate upward by 2 units every 3 days if fasting glucose remains above goal 3
Important Caveats
Do not mix or dilute Tresiba with any other insulin. If the patient is on prandial insulin, maintain those doses initially but be prepared to adjust—research shows prandial insulin requirements may decrease by approximately 10% after switching 2.
The patient is likely on twice-daily Lantus because once-daily dosing failed to provide 24-hour coverage. Tresiba's ultra-long duration of action specifically addresses this issue, making once-daily dosing feasible 4. Studies demonstrate that switching from twice-daily glargine to once-daily degludec improves HbA1c, reduces hypoglycemia (particularly nocturnal), and decreases glucose variability 4, 5.
Expected Outcomes
Within 12 weeks, expect:
- Improved fasting glucose control
- Reduced nocturnal hypoglycemia risk (rate ratio 0.64-0.75 vs glargine) 5
- Potential 17-24% reduction in total basal insulin requirements 4
- More stable day-to-day glucose patterns
Monitor closely and adjust based on individual response, but starting at 48 units once daily provides the safest initial conversion with the lowest hypoglycemia risk while maintaining glycemic control.