What is the proper procedure for switching an adult patient with type 1 or type 2 diabetes from Tresiba (insulin degludec) to Lantus (insulin glargine)?

Switching from Tresiba to Lantus

When switching from Tresiba (insulin degludec) to Lantus (insulin glargine), use a 1:1 unit-for-unit conversion and administer the first dose of Lantus 24 hours after the last dose of Tresiba, with close glucose monitoring for the first week due to the shorter duration of action of Lantus. 1

Conversion Protocol

Timing and Dosing

• Administer the first Lantus dose exactly 24 hours after the last Tresiba injection to avoid overlap, as Tresiba has a duration of action exceeding 42 hours while Lantus provides approximately 24 hours of coverage 2
• Use a 1:1 unit conversion (same total daily basal dose) as the starting point 1, 3
• For patients on once-daily Tresiba, switch to once-daily Lantus at the same time of day 1, 3

Critical Monitoring Requirements

• Check fasting blood glucose daily for the first 7-14 days after switching to assess adequacy of basal coverage 1
• Monitor for breakthrough hyperglycemia, particularly in the 18-24 hour window after Lantus injection, as Lantus may not provide the same consistent 24-hour coverage as Tresiba 3, 2
• If fasting glucose rises above 180 mg/dL on consecutive days, increase Lantus by 4 units every 3 days until fasting glucose reaches 80-130 mg/dL 1

Dose Titration After Conversion

Standard Titration Algorithm

• Increase Lantus by 2 units every 3 days if fasting glucose is 140-179 mg/dL 1
• Increase Lantus by 4 units every 3 days if fasting glucose is ≥180 mg/dL 1
• Target fasting plasma glucose of 80-130 mg/dL 1
• If hypoglycemia occurs (glucose <70 mg/dL), reduce the dose by 10-20% immediately 1

Potential Need for Twice-Daily Dosing

• Consider splitting Lantus to twice-daily administration if inadequate 24-hour coverage becomes evident, particularly if morning fasting glucose is elevated despite adequate evening pre-dinner glucose 1
• This is more likely in patients with type 1 diabetes who may have experienced stable control on Tresiba's ultra-long action profile 1, 2

Special Considerations

Hypoglycemia Risk

• Patients may experience slightly higher rates of nocturnal hypoglycemia with Lantus compared to Tresiba, as clinical trials showed Tresiba reduced nocturnal hypoglycemia by 25% compared to insulin glargine 2
• Educate patients to treat any glucose <70 mg/dL immediately with 15 grams of fast-acting carbohydrate 1

Maintaining Prandial Coverage

• Continue the same prandial insulin regimen unchanged during the basal insulin switch 1
• Prandial insulin doses should only be adjusted based on postprandial glucose patterns, not because of the basal insulin change 1

Foundation Therapy

• Continue metformin unless contraindicated when switching basal insulins, as this combination provides superior glycemic control with reduced insulin requirements 1

Common Pitfalls to Avoid

• Do not overlap the two basal insulins by giving Lantus before Tresiba has cleared, as this creates unnecessary hypoglycemia risk 1
• Do not assume the conversion will be seamless—Tresiba's ultra-long duration of action (>42 hours) provides more stable coverage than Lantus's 24-hour profile, so some patients may require dose adjustments or twice-daily Lantus 3, 2
• Do not delay dose adjustments if fasting glucose patterns show inadequate control—titrate every 3 days as needed rather than waiting weeks 1
• Do not stop monitoring after the first few days—continue daily fasting glucose checks for at least 1-2 weeks to ensure stable conversion 1