Are Levemir (insulin detemir) and Lantus (insulin glargine) doses interchangeable?

Levemir and Lantus Doses Are Not Directly Interchangeable

When switching between insulin detemir (Levemir) and insulin glargine (Lantus), doses are not directly interchangeable and require adjustment, typically with a 10-20% dose reduction when switching from Levemir to Lantus due to their different pharmacokinetic profiles. 1

Pharmacological Differences Between Levemir and Lantus

• Duration of action: Both are long-acting insulin analogs, but they have different durations of action:

  • Levemir (insulin detemir): 12-24 hours 1
  • Lantus (insulin glargine): Up to 24 hours 1

• Binding properties: Levemir is 98-99% albumin-bound in plasma, which affects its distribution and duration of action 2

• Dosing frequency:

  • Levemir may require twice-daily dosing in approximately 55% of patients to maintain optimal glucose control 3
  • Lantus is typically administered once daily 3

Conversion Guidelines

When Switching from Levemir to Lantus:

1. Initial dose adjustment: Reduce the total daily dose by 10-20% when switching from Levemir to Lantus 1

   • Example: If a patient is on 20 units of Levemir daily, start with 16-18 units of Lantus

2. Dosing frequency adjustment:

   • If patient was on twice-daily Levemir, consolidate to once-daily Lantus (typically at bedtime) 4
   • For patients on once-daily Levemir, maintain once-daily dosing with Lantus but still consider the 10-20% dose reduction 1

When Switching from Lantus to Levemir:

1. Initial dose conversion:

   • May start with a unit-for-unit conversion 1
   • Be prepared to increase the total daily dose of Levemir by 20-30% compared to Lantus 3

2. Dosing frequency consideration:

   • Assess the need for twice-daily dosing of Levemir if fasting glucose targets are not achieved with once-daily dosing 3
   • If pre-dinner plasma glucose remains >7.0 mmol/L despite good fasting glucose control, consider adding a morning dose of Levemir 3

Monitoring After Switching

1. Frequent blood glucose monitoring: Check glucose levels at least 4 times daily for the first week after switching 5

2. Pay special attention to:

   • Fasting morning glucose levels
   • Pre-dinner glucose levels (particularly when switching from Lantus to Levemir)
   • Nocturnal hypoglycemia risk

3. Dose titration: Adjust doses by 1-2 units (or 10-15% for higher doses) once or twice weekly until target fasting glucose is achieved 5

Clinical Considerations and Pitfalls

• Weight effects: Levemir is associated with slightly less weight gain compared to Lantus (2.7 vs 3.5 kg over 52 weeks) 3

• Injection site reactions: More common with Levemir (4.5%) than with Lantus (1.4%) 3

• Dosing efficiency: Lantus may achieve similar glycemic control with lower insulin doses compared to Levemir (0.44 IU/kg vs 0.78 U/kg) 3

• Common pitfall: Assuming direct interchangeability can lead to either hypoglycemia (if Levemir dose is directly converted to Lantus) or hyperglycemia (if Lantus dose is directly converted to Levemir without considering potential need for twice-daily dosing)

• Special situation - hospital transitions: When transitioning from insulin pump therapy to intravenous insulin in hospital settings, calculate the total basal rate from the pump and use this to determine appropriate IV insulin dosing 1

Efficacy Comparison

Clinical studies show that both insulins achieve similar glycemic control:

• HbA1c reduction is comparable between Levemir and Lantus in both type 1 and type 2 diabetes 3
• Fasting plasma glucose improvements are similar 3
• Hypoglycemia risk is comparable between both insulins when properly dosed 3

Remember that individual patient response may vary, and close monitoring with appropriate dose adjustments is essential when switching between these two basal insulins.