Alternatives to Insulin Glargine-Yfgn If You Can't Fill Your Prescription

With Semglee (insulin glargine-yfgn) discontinued in December 2025, many patients need to switch to a different long-acting basal insulin. The good news: there are several effective alternatives, and for some switches, you won't even need a new prescription. This guide breaks down your best options, how they compare, and what to watch for when switching.

Important: Talk to Your Doctor Before Switching Insulins

Insulin products are not all identical, even when they contain the same active ingredient. Differences in concentration, duration of action, or formulation can affect your blood sugar control. Always discuss any insulin change with your doctor or endocrinologist before switching, and monitor your blood glucose more closely during any transition period.

Option 1: Lantus (Insulin Glargine) — No New Prescription Needed

Lantus is the reference product that insulin glargine-yfgn (Semglee) was approved against. Because insulin glargine-yfgn carries the FDA interchangeable designation, pharmacists can substitute Lantus for insulin glargine-yfgn at the point of dispensing — without a new prescription.

Dose: Unit-for-unit switch (same dose as insulin glargine-yfgn)

Forms: 10 mL vials and 3 mL SoloStar pens (100 units/mL)

Cash price: After Sanofi's 78% list price reduction, approximately $80–$100 per vial or box of pens. Sanofi Valyou Savings Program: $35/month regardless of insurance status

Availability: Generally available, though Solostar pens have experienced intermittent back-orders due to surging demand after Semglee discontinuation. Vials remain available.

Option 2: Basaglar (Insulin Glargine) — New Prescription Required

Basaglar, made by Eli Lilly, is a "follow-on" insulin glargine product that works similarly to Lantus and Semglee. It is not FDA-designated as interchangeable, so a new prescription from your doctor is required to switch.

Dose: Unit-for-unit switch from other insulin glargine 100 units/mL products

Forms: 3 mL KwikPens (100 units/mL)

Cost: Eli Lilly's $35/month cap applies regardless of insurance status. Generally good availability.

Option 3: Rezvoglar (Insulin Glargine-Aglr) — New Prescription Required

Rezvoglar, approved in December 2021 by Eli Lilly, is a biosimilar to Lantus (not an interchangeable). It is clinically equivalent to other insulin glargine 100 units/mL products but requires a new prescription to switch.

Forms: 3 mL KwikPens (100 units/mL)

Availability: Growing availability in 2026 as a newer biosimilar option from Eli Lilly

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Option 4: Toujeo (Insulin Glargine U-300) — New Prescription, Dose Adjustment Required

Toujeo is a concentrated insulin glargine product at 300 units/mL (three times the concentration of Semglee). It has a longer duration of action and may cause less nocturnal hypoglycemia. However, when switching from 100 units/mL glargine to Toujeo, the starting dose is typically 80% of your previous dose — not unit-for-unit — and close monitoring is required.

Note: Toujeo is not interchangeable with any other insulin. A new prescription is always required.

Option 5: Levemir (Insulin Detemir) — New Prescription, Different Drug Class

Levemir (insulin detemir) is a different long-acting insulin analog. It works similarly to insulin glargine but has a slightly different duration (12–24 hours vs. ~24 hours), so some patients may need twice-daily dosing. It is an option if insulin glargine products are unavailable, but requires careful transition with your doctor.

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Option 6: Tresiba (Insulin Degludec) — Ultra-Long Acting, New Prescription Required

Tresiba (insulin degludec) is an ultra-long-acting basal insulin with a duration of action exceeding 42 hours. It offers more dosing flexibility (can be given at different times of day) and is associated with lower risk of nocturnal hypoglycemia in some patients. Available in U-100 and U-200 FlexTouch pens.

Quick Comparison: Which Alternative Is Best for You?

Need to switch without a new prescription? → Lantus (interchangeable substitution)

Looking for the lowest cost with a new prescription? → Basaglar ($35/month via Eli Lilly)

Want the longest duration and most flexible dosing? → Tresiba (degludec)

Concerned about nocturnal hypoglycemia? → Toujeo (U-300 glargine)

If you want to keep using insulin glargine-yfgn rather than switch, use medfinder to locate which pharmacies near you still carry it. Or read our full explainer on why insulin glargine-yfgn is so hard to find in 2026.