What is the best approach for an adult patient with type 1 or type 2 diabetes to switch from Tresiba (insulin degludec) to Levemir (insulin detemir)?

Switching from Tresiba to Levemir: Practical Approach

Direct Conversion Strategy

Switch on a unit-to-unit basis initially, but expect to increase the Levemir dose by approximately 38% to achieve equivalent glycemic control. When converting from Tresiba (insulin degludec) to Levemir (insulin detemir), the total daily dose of detemir should be approximately 38% higher than the total daily dose of degludec 1.

Step-by-Step Conversion Protocol

Initial Dose Calculation

• Start with the current Tresiba dose and increase by 38% for the total daily Levemir dose 1
• For example, if a patient is on 30 units of Tresiba once daily, initiate Levemir at approximately 41 units total daily (30 × 1.38 = 41.4 units)
• Divide this total dose into twice-daily administration - Levemir typically requires twice-daily dosing to provide adequate 24-hour coverage, unlike Tresiba's ultra-long duration 2, 3

Dosing Schedule

• Administer Levemir twice daily (morning and bedtime) rather than once daily 3, 4
• Split the calculated total daily dose approximately 50:50 between morning and evening doses initially 4
• For the example above: 20-21 units in the morning and 20-21 units at bedtime
• Alternatively, give the larger portion at bedtime if nocturnal hyperglycemia is a concern 4

Titration and Monitoring

Immediate Monitoring Requirements

• Check fasting blood glucose daily during the first 1-2 weeks of the switch 5
• Monitor pre-dinner glucose to assess adequacy of morning Levemir dose
• Target fasting glucose: 80-130 mg/dL 1

Dose Adjustments

• Adjust each Levemir dose independently based on glucose patterns 1
• If fasting glucose is 140-179 mg/dL, increase the bedtime Levemir dose by 2 units every 3 days 1
• If fasting glucose is ≥180 mg/dL, increase the bedtime Levemir dose by 4 units every 3 days 1
• Adjust the morning Levemir dose based on pre-dinner glucose readings using the same algorithm 1
• If hypoglycemia occurs, reduce the corresponding dose by 10-20% immediately 1

Key Pharmacologic Differences to Anticipate

Duration of Action

• Tresiba provides ultra-long action (>42 hours), while Levemir provides up to 24 hours of coverage 2, 6
• This shorter duration necessitates twice-daily dosing with Levemir for most patients 2, 3

Variability and Predictability

• Levemir has less intrapatient variability than NPH insulin but may have slightly more variability than Tresiba 2, 3
• Expect more consistent day-to-day glucose patterns with both insulins compared to NPH 2

Hypoglycemia Risk

• Both insulins have lower nocturnal hypoglycemia rates compared to NPH insulin 7, 2
• Levemir demonstrates a lower risk of nocturnal hypoglycemia specifically 2, 3, 4
• However, switching from Tresiba may initially increase hypoglycemia risk if doses are not properly adjusted, as observational data shows Tresiba is associated with lower overall hypoglycemia rates 8

Weight Effects

• Levemir is associated with less weight gain than NPH insulin, particularly in type 2 diabetes 7, 2
• Expect minimal weight gain in type 1 diabetes and less weight gain than NPH in type 2 diabetes 2, 4

Critical Pitfalls to Avoid

Dosing Errors

• Never use a simple 1:1 unit conversion without the 38% dose increase - this will result in inadequate basal coverage 1
• Do not attempt once-daily Levemir dosing in most patients - the shorter duration of action compared to Tresiba makes twice-daily dosing necessary for adequate 24-hour coverage 2, 3

Monitoring Failures

• Do not wait longer than 3 days between dose adjustments during active titration - this unnecessarily prolongs time to achieve glycemic targets 1
• Avoid ignoring pre-dinner glucose patterns - this reflects the adequacy of morning Levemir and must be monitored separately from fasting glucose 1

Foundation Therapy

• Continue metformin unless contraindicated - do not discontinue when switching basal insulins 1, 5, 9
• Metformin provides complementary glucose-lowering effects and reduces total insulin requirements 5, 9

Special Considerations

When Basal Insulin Alone Is Insufficient

• If basal insulin exceeds 0.5 units/kg/day and glucose remains elevated, the problem is likely insufficient prandial coverage rather than inadequate basal insulin 1, 9
• Consider adding prandial insulin rather than continuing to escalate Levemir doses beyond this threshold 1

High-Risk Populations

• For elderly patients (>65 years), those with renal impairment, or poor oral intake, use lower starting doses (reduce by 20-50%) 1
• Monitor more frequently for hypoglycemia in these populations 1

Expected Timeline

• Initial stabilization: 1-2 weeks with daily fasting glucose monitoring 5
• Full dose optimization: 2-4 weeks with adjustments every 3 days 1
• Reassess HbA1c at 3 months to evaluate overall glycemic control 1