Yes, you can temporarily substitute Lantus for Basaglar at the same dose.
Basaglar and Lantus are both insulin glargine 100 units/mL products that can be substituted unit-for-unit without dose adjustment 1, 2. The FDA labeling for Basaglar explicitly states: "If changing patients from another insulin glargine product, 100 units/mL, to BASAGLAR, the dose of BASAGLAR should be the same as the other insulin glargine product, 100 units/mL" 1.
Key Evidence Supporting 1:1 Substitution
FDA-Approved Equivalence
Both products contain insulin glargine 100 units/mL with nearly identical formulations and are administered subcutaneously once daily at the same time each day 1, 2. The FDA drug labels confirm direct interchangeability at equivalent doses between these two insulin glargine 100 units/mL products.
Clinical Trial Data
Phase III ELEMENT trials demonstrated that Basaglar (LY2963016 insulin glargine) and Lantus are equivalent in efficacy with similar glycemic control, safety profiles, and hypoglycemia risk 3. Real-world evidence from a large Saudi Arabian healthcare system showed no significant difference in A1C levels when switching between these products (mean A1C difference 0.18, p=0.503) 4.
Pharmacokinetic/Pharmacodynamic Similarity
Phase I euglycemic clamp studies confirmed that Basaglar demonstrates similar pharmacodynamic parameters, duration of action, and pharmacokinetics to Lantus 3. This structural and functional similarity supports the 1:1 dose conversion.
Important Monitoring Considerations
While the dose remains the same, increase blood glucose monitoring frequency during the transition period 1. The FDA labeling for both products emphasizes that any insulin regimen change may affect glycemic control and requires closer medical supervision 1, 2.
Watch for:
- Hypoglycemia risk: Though equivalent between products, monitor for any unexpected drops in blood glucose, particularly if the patient has been injecting into areas of lipodystrophy 1
- Injection site rotation: Ensure proper rotation to avoid lipodystrophy or localized cutaneous amyloidosis, which can affect insulin absorption 1
- Timing consistency: Maintain the same once-daily administration time regardless of which product is used 1, 2
Common Pitfalls to Avoid
Do not confuse with insulin glargine 300 units/mL (Toujeo): If switching from Toujeo to either Basaglar or Lantus, you would need to reduce the dose to 80% of the Toujeo dose 1. This question specifically addresses switching between two 100 units/mL products, which requires no dose adjustment.
Do not mix with other insulins: Both Basaglar and Lantus should never be diluted or mixed with other insulin products due to their acidic pH 5, 1.
The real-world evidence shows that switching between these insulin glargine 100 units/mL products maintains glycemic control without requiring dose adjustments, though some studies suggest monitoring for potential minor variations in insulin requirements over time 4.