Insulin Glargine-Yfgn Shortage: What Providers and Prescribers Need to Know in 2026

The discontinuation of Semglee (insulin glargine-yfgn) on December 31, 2025 has created a clinically and administratively complex situation for prescribers managing patients with Type 1 and Type 2 diabetes. The supply disruption is not a simple product shortage — it is a market-wide transition that has affected formularies, pharmacy inventories, patient copays, and prescribing workflows simultaneously. This briefing provides the clinical and operational context you need to manage your patients effectively in 2026.

Background: What Was Insulin Glargine-Yfgn (Semglee)?

Insulin glargine-yfgn (Semglee) was approved by the FDA on July 28, 2021 as the first interchangeable biosimilar insulin product in US history. Its interchangeable designation — granted under the BPCIA pathway — allowed pharmacists to substitute Semglee for Lantus (insulin glargine) at the point of dispensing without prescriber intervention, similar to generic drug substitution. This made it a significant access tool for patients and a preferred product on many formularies.

Manufactured by Biocon Biologics (under partnership with Viatris/Mylan), Semglee was available as 100 units/mL in 10 mL vials and 3 mL prefilled pens. Clinical studies (INSTRIDE 1 and related trials) confirmed equivalent glycemic control to Lantus with a similar safety profile.

The Discontinuation: Timeline and Current Supply Picture

February 2025: Biocon announced anticipated pen shortage. Shortage persisted beyond projected March resolution.

March–August 2025: Multiple payers added Lantus to formularies as emergency coverage. ASHP shortage listings active for glargine-yfgn. Regional intensification in Pacific NW and Northeast.

December 31, 2025: Biocon formally discontinued all Semglee vials and pens — a business decision, not a safety action.

January 2026: Civica Rx launched unbranded insulin glargine-yfgn pens at $45/5-pen box, the lowest list price for any long-acting insulin in the US. Generic vials and pens from Winthrop remain available. Demand shifted heavily to Lantus, creating intermittent Solostar pen back-orders.

Clinical Implications: What Prescribers Need to Manage

1. Interchangeability and the Dispense-as-Written Question

Insulin glargine-yfgn was FDA-designated as interchangeable with Lantus, meaning pharmacists could substitute between Lantus and insulin glargine-yfgn in either direction without prescriber intervention. This interchangeability designation still applies to other products bearing the glargine-yfgn nonproprietary name (e.g., Civica Rx unbranded version). However:

Substitution only applies Lantus ↔ glargine-yfgn. Switching to Basaglar, Rezvoglar, Levemir, or Toujeo requires a new prescription.

If you want a specific product dispensed (e.g., you prefer Civica Rx over Lantus for cost reasons), write 'Dispense as Written' or specify the product name on the prescription.

State laws on biosimilar substitution notification vary. Some states require pharmacists to notify the prescriber when a substitution occurs.

2. Dose Conversion When Switching Products

Lantus, Basaglar, Rezvoglar, unbranded glargine-yfgn (Civica): All 100 units/mL products. Switch is unit-for-unit. Monitor for first few days.

Toujeo (300 units/mL) from 100 units/mL glargine: Start at same number of units but expect 10–15% dose increase may be needed in first weeks due to pharmacokinetic differences. Monitor closely.

Levemir (insulin detemir): Start at same unit dose; note shorter duration in some patients may require twice-daily dosing. Monitor A1C and SMBG closely.

3. Formulary and Prior Authorization Challenges

Many payers carried Semglee as their sole preferred insulin glargine product. Post-discontinuation, patients switching to Lantus or Basaglar may face:

New prior authorization requirements for the replacement product

Formulary tier changes affecting patient copays

Step therapy requirements before brand Lantus is covered

When writing prior authorization letters, cite medical necessity and the documented shortage/discontinuation as grounds for urgent formulary exception. Note that the Inflation Reduction Act capped Medicare insulin copays at $35/month, which helps insured Medicare patients regardless of formulary position.

Cost Guidance to Share With Patients

Civica Rx insulin glargine-yfgn: $45/5 pens ($9/pen). Lowest list price on market.

Lantus — Sanofi Valyou Savings Program: $35/month regardless of insurance status. Available at sanofi.com.

Basaglar (Eli Lilly): Eli Lilly's $35/month cap applies. Strong availability.

Medicare patients: IRA $35/month cap on all covered insulin applies under Part D.

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Tools to Help Your Patients Find Stock

Encourage patients who are having difficulty filling their basal insulin to use medfinder's provider tools. medfinder contacts pharmacies in your patient's area to check which ones have their specific prescription in stock, and texts the results to the patient. This eliminates the need for patients to spend hours calling pharmacies — a particular burden for elderly or high-risk patients.

For a detailed guide on helping your patients navigate this transition, see: How to Help Your Patients Find Insulin Glargine-Yfgn in Stock: A Provider's Guide.