What is the recommended dosing strategy when converting a patient from Tresiba (insulin degludec) to Toujeo (insulin glargine)?

Tresiba to Toujeo Conversion

Direct Conversion Recommendation

Convert Tresiba (insulin degludec) to Toujeo (insulin glargine U-300) on a unit-for-unit basis initially, then reduce the dose by 10-20% for patients at high risk of hypoglycemia, with close monitoring and titration based on fasting glucose over the first 2-4 weeks. 1

Understanding the Key Pharmacologic Differences

The conversion requires careful consideration because these insulins have distinct pharmacokinetic profiles:

• Tresiba (insulin degludec) has an ultra-long duration of action exceeding 42 hours with a flat, stable glucose-lowering profile and notably less day-to-day variability than insulin glargine 2, 3
• Toujeo (insulin glargine U-300) has a longer duration of action than standard U-100 glargine (Lantus) but modestly lower efficacy per unit administered, with a flatter and longer pharmacodynamic profile than U-100 formulations 4, 5

The half-life of degludec is approximately 17-21 hours (roughly double that of glargine), which means it takes longer to reach steady state and longer to wash out after discontinuation 3.

Step-by-Step Conversion Protocol

Initial Dose Calculation

1. Calculate total daily Tresiba dose currently being administered 1
2. For standard-risk patients: Convert unit-for-unit to once-daily Toujeo 1
3. For high-risk patients (elderly, renal impairment, history of severe hypoglycemia): Reduce the converted dose by 10-20% 1

High-Risk Patient Identification

Patients requiring dose reduction include:

• Age >65 years 6
• Renal failure or impairment 6
• History of severe or frequent hypoglycemia 1
• Poor or unpredictable oral intake 6

Critical Monitoring Requirements

First 2-4 Weeks Post-Conversion

• Daily fasting blood glucose monitoring is essential during the transition period 1
• Assess glucose patterns every 3 days and adjust dose accordingly 6, 1
• If hypoglycemia occurs, immediately reduce the dose by 10-20% and reassess 6, 1

Titration Algorithm After Conversion

Once on Toujeo, adjust based on fasting glucose targets:

• If fasting glucose ≥180 mg/dL: Increase by 4 units every 3 days 6
• If fasting glucose 140-179 mg/dL: Increase by 2 units every 3 days 6
• Target fasting glucose: 80-130 mg/dL 6
• If fasting glucose <80 mg/dL on ≥2 occasions per week: Decrease by 2 units 6

Important Considerations During Transition

Overlapping Insulin Effect

Because Tresiba has such a long duration of action (>42 hours), there will be residual insulin activity for several days after discontinuation 2, 3. This creates a period where both insulins are active:

• The first 3-5 days after switching carry higher hypoglycemia risk due to overlapping insulin effects 3
• Consider starting Toujeo at the lower end of the dosing range (with 10-20% reduction) if concerned about this overlap 1

Bioequivalence Considerations

Toujeo and standard Lantus are NOT bioequivalent - daily insulin requirements are typically slightly higher with Toujeo (U-300) than with standard glargine (U-100), though this is less relevant when converting from Tresiba 5. The shift from any basal insulin to Toujeo may require dose adjustment and reinforced glucose monitoring 5.

Common Pitfalls to Avoid

• Do not assume immediate steady-state: Tresiba's ultra-long half-life means it takes approximately 2-3 days to fully wash out, while Toujeo reaches steady state more quickly 3
• Do not delay dose adjustments: If glucose patterns clearly indicate need for adjustment after 3 days, make the change rather than waiting unnecessarily 6
• Do not adjust prandial insulin during basal conversion: Keep mealtime insulin doses stable initially to isolate the effect of the basal insulin change 7
• Do not switch multiple medications simultaneously: This makes it impossible to identify the cause of glycemic changes 7

Foundation Therapy Maintenance

• Continue metformin unless contraindicated throughout the conversion process 6
• Maintain other non-insulin diabetes medications as prescribed unless specifically contraindicated 6

When to Consider Alternative Approaches

If basal insulin requirements exceed 0.5 units/kg/day during or after conversion, consider adding prandial insulin or a GLP-1 receptor agonist rather than continuing to escalate basal insulin alone 6, 7. Signs of "overbasalization" include:

• Basal dose >0.5 units/kg/day 6
• Bedtime-to-morning glucose differential ≥50 mg/dL 6
• Recurrent hypoglycemia 6
• High glucose variability 6