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Lantus (insulin glargine) was first approved in the US in 2000 as a long-acting basal insulin. Over the years, Lantus became one of the most prescribed basal insulins. On the other hand, Semglee (insulin glargine-yfgn) is a biosimilar of Lantus.

Biosimilars are biological medications that are highly similar to an already approved reference product but manufactured by a different company. They must demonstrate no clinically meaningful differences in safety, purity, or potency.

Semglee was first approved by the FDA as a biosimilar in June 2020 and later gained interchangeable status in July 2021. This means that pharmacists can substitute Semglee for Lantus without the prescriber’s approval, subject to state laws.

While the active ingredient is the same, there are important distinctions in how they are regulated, manufactured, formulated, and priced. Below, we’ll explain those differences so that you can make an informed choice.

Key Takeaways

  • Semglee is an interchangeable biosimilar of Lantus. It was developed by Biocon Biologics and distributed by Viatris. It uses the same insulin glargine molecule but is manufactured in Pichia pastoris and carries the suffix “-yfgn”.
  • In 2023, the wholesale acquisition cost for Lantus was about $292 per month, while Semglee cost around $269. However, Sanofi announced a 78% price cut for Lantus and a $35 copay cap in 2024.
  • Both products have identical dosing and administration. They are injected once daily and start with 0.2 units/kg or 10 units for insulin-naïve patients. Pens deliver 1-80 units per dose and hold 300 units of insulin.
  • The inactive ingredients differ only in the preservative (m-cresol vs metacresol), and both products have a pH around 4 with similar stabilizers.
  • Their efficacy and safety are equivalent. Trials showed no significant differences in HbA1c reduction or hypoglycemia between Semglee and Lantus.
  • At Pharma Giant, a 5-pen package of Semglee pen costs $99.95, while a 5-pen package of Lantus Solostar pen costs $177.

Manufacturing and naming differences

Lantus is manufactured and marketed by Sanofi, a French multinational pharmaceutical company. Sanofi owns the intellectual property for insulin glargine and sells it under the Lantus brand worldwide.

Semglee was developed by Biocon Biologics, an Indian biotechnology company, and is distributed in the United States by Viatris (formerly Mylan).

The non-proprietary name for Lantus is insulin glargine. When a biosimilar is approved, a four-letter suffix is appended to the non-proprietary name to distinguish it. So, Semglee is technically insulin glargine-yfgn. But both names denote the same active molecule.

When Semglee is dispensed as an authorized generic, the product is labeled simply “insulin glargine U-100” without the suffix. You might see Semglee, insulin glargine-yfgn, or unbranded insulin glargine on pharmacy shelves. These are essentially the same medicine from Biocon/Viatris.

Cost and accessibility

A major reason biosimilars exist is to lower costs. In 2023, the Biosimilars Council released a market analysis comparing the wholesale acquisition cost (WAC) of Lantus and biosimilar products. According to that report, the WAC for a 30-day supply of Lantus was $292, while the WAC for the branded Semglee interchangeable product was $269.

In March 2023, Sanofi also announced that it would cut the list price of Lantus by 78%, effective January 2024, and cap out-of-pocket costs at $35 per month for all patients with commercial insurance.

Insurance coverage

The Biosimilars Council analysis also looked at how often doctors start patients on each product. Six quarters after the launch of interchangeable Semglee, Lantus still held 54% of new-to-brand prescriptions and 78% of total prescriptions. Semglee’s uptake was concentrated in the commercial insurance channel (24% share), while its share in Medicare and Medicaid was 6% or less.

The report cited limited payer coverage as the main reason for the slow adoption of biosimilar insulin. Many patients who attempted to fill unbranded insulin glargine prescriptions were not approved.

Sanofi’s price reduction may further narrow cost differences between Lantus and Semglee, especially for those with commercial insurance who can use the $35 monthly copay program. If you don’t have insurance, you may still find unbranded insulin glargine cheaper.

Discontinuation of the Semglee brand

Biocon discontinued Semglee vials and pens on December 31, 2025, but unbranded insulin glargine-yfgn (the authorized generic) remains available. If you previously used Semglee, you may now receive the generic insulin glargine-yfgn or another biosimilar such as Rezvoglar or Basaglar. Lantus and its SoloStar pens remain on the market.

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Formulation and ingredients

Though Semglee and Lantus share the same active ingredient, there are subtle differences in their formulations due to different manufacturing processes and excipients. These differences are minor and do not change how the drug works, but they can matter for people with sensitivities to certain additives.

Active ingredient

Both products contain insulin glargine, a long-acting human insulin analog. In Lantus, the insulin glargine molecule is produced using recombinant DNA technology in Escherichia coli, while Semglee uses the yeast Pichia pastoris. After production, both insulins are purified and formulated into a clear, colorless solution.

Excipients and pH

With Lantus, each mL of solution contains 100 units of insulin glargine with:

    • glycerol 85% (20 mg)
    • m-cresol (2.7 mg)
    • zinc (30 µg)
    • water for injection

The vial formulation also contains polysorbate 20. The solution is adjusted to a pH of approximately 4 using hydrochloric acid and sodium hydroxide.

On the other hand, each mL of Semglee contains 100 units of insulin glargine-yfgn with:

    • glycerol (20 mg)
    • metacresol (2.7 mg)
    • zinc chloride (content adjusted to provide 30 µg of zinc)
    • water for injection

The vial formulation also contains polysorbate 20 (20 µg). The pH is adjusted to approximately 4 using hydrochloric acid and sodium hydroxide. Metacresol is closely related to m-cresol, and both serve as preservatives.

Because these excipients are nearly identical, the pH and stability of the two products are the same. There is no evidence that the excipient difference (m-cresol versus metacresol) leads to clinically meaningful differences in safety or efficacy.

Dosing and administration

Both products are prescribed based on the individual’s insulin needs, blood glucose, and previous insulin therapy. They have the same concentration (100 units/mL) and are injected once daily at the same time each day.

Similarities and minor differences include the following points:

  • Starting doses – Patients with type 1 diabetes who switch from another insulin start with about one-third of the total daily insulin requirement. Adults with type 2 diabetes who have not used insulin before typically begin at 0.2 units per kilogram or up to 10 units once daily. These recommendations are identical for Lantus and Semglee.
  • Adjustment rules – Doses should be individualized and adjusted based on blood glucose monitoring, meal patterns, and physical activity. Consult your healthcare provider before making changes to avoid hypo- or hyperglycemia.
  • Combination therapy – In type 1 diabetes, both Lantus and Semglee must be used alongside rapid-acting mealtime insulin. In type 2 diabetes, they can be used alone or with oral antidiabetic medicines.
  • Injection sites – The insulins should be injected subcutaneously into the abdomen, thigh, or upper arm. Injection sites should be rotated to reduce the risk of lipodystrophy or localized cutaneous amyloidosis.
  • Mixing and pumps – Neither product should be diluted or mixed with other insulins, nor should they be used in insulin pumps.
  • Dosing increments – Both the Lantus SoloStar and Semglee pens dial doses in 1-unit increments up to 80 units per injection. This means that fine-tuning of doses is the same for both products.

Presentation and delivery devices

Design choices can make a big difference, especially when it comes to how insulin is delivered, handled, and experienced day to day. Here’s how Semglee and Lantus compare:

Vials

Lantus and Semglee both come in 10 mL multiple-dose vials containing 100 units/mL. Vials must be used with insulin syringes. The vials include the same concentration and similar excipients. Neither product should be shared among patients, and needles must be discarded after each injection.

Prefilled pens

The pens function almost identically. If you’re switching from Lantus to Semglee or vice versa, read the instructions for use, but you will find the steps largely the same.

Feature

 Lantus SoloStar

Semglee Prefilled Pen
Total insulin per pen

300 units

300 units
Dose selection 1-80 units in 1-unit steps 1-80 units in 1-unit steps
Needle compatibility BD Ultra-Fine needles recommended BD Ultra-Fine needles recommended
Design Disposable pen with dial and injection button; moves plunger only when 300 units used Similar disposable pen design
Color and branding Purple/grey with “Lantus SoloStar” label (branding may vary by region) Green/white with “Semglee” label; generic insulin glargine pens may be white and green

As mentioned earlier, Biocon discontinued the branded Semglee pens at the end of 2025. The generic insulin glargine-yfgn pens remain available and use the same design.

Other insulin glargine pens on the market include Basaglar (Lilly) and Rezvoglar (Lilly). Sanofi also sells Toujeo pens containing insulin glargine at 300 units/mL, but these are not interchangeable with the 100 units/mL formulations.

Clinical efficacy and safety

To become a biosimilar, Semglee had to prove that it offers the same efficacy and safety as Lantus. This was done through the INSTRIDE clinical trials program.

    • INSTRIDE 1 – This 52-week phase III study included 558 participants with type 1 diabetes who were already using mealtime insulin lispro. The mean change in HbA1c was 0.14% for Semglee and 0.11% for reference insulin glargine (Lantus). The results were within the non-inferiority margin, meaning Semglee was just as effective. Secondary outcomes such as fasting plasma glucose, total insulin dose, and hypoglycemia rates showed no clinically significant differences between groups.
    • INSTRIDE 2 – A trial in 560 insulin-naïve or insulin-experienced adults with type 2 diabetes. Participants received either Semglee or reference insulin glargine in addition to oral antidiabetic drugs for 24 weeks. The mean HbA1c reduction was 0.60% for Semglee and 0.66% for reference insulin glargine. Again, the difference was not clinically significant. Changes in fasting glucose, insulin doses, and body weight were also similar.
    • INSTRIDE 3 – In this study, adults with type 1 diabetes who had completed INSTRIDE 1 were randomized to continue reference insulin glargine or switch between Semglee and reference insulin glargine in 12-week intervals. After 36 weeks, mean HbA1c changes differed by only 0.01%, and no significant differences were observed in fasting glucose, mealtime insulin doses, or body weight. This study supported the interchangeability designation because switching did not affect efficacy or safety.

These trials collectively show that Semglee delivers the same glycemic control as Lantus in both type 1 and type 2 diabetes. Hypoglycemia was the most common adverse event in all groups, but rates were comparable.

Safety profile and side effects

Because Semglee and Lantus share the same active ingredient and similar excipients, their safety profiles are nearly identical. Both labels list the following common adverse reactions:

    • Hypoglycemia (low blood sugar) – the most frequent and potentially serious side effect. Symptoms can include shakiness, confusion, sweating, and, in severe cases, seizures or loss of consciousness.
    • Allergic reactions – including rash, itching, or swelling at the injection site.
    • Injection-site reactions, lipodystrophy (pits or lumps in the skin), and localized cutaneous amyloidosis – these occur when injections are not rotated.
    • Edema (swelling) and weight gain – due to the anabolic effects of insulin.

Serious warnings include the following items.

    • Hypoglycemia due to medication errors – Using the wrong insulin, mixing insulins, or misreading the dose can cause severe hypoglycemia.
    • Hypersensitivity and anaphylaxis – Rare but life-threatening allergic reactions may occur. Treatment should be stopped, and medical care sought.
    • Hypokalemia (low potassium) – Insulin drives potassium into cells, potentially causing cardiac arrhythmias.
    • Heart failure with thiazolidinediones – Both labels warn that combining insulin glargine with thiazolidinediones (e.g., pioglitazone) can cause fluid retention and heart failure.
    • Use during pregnancy and lactation – Insulin glargine has been used safely in pregnancy when blood sugar is controlled, but dosing may need adjustment. Neither product is recommended for diabetic ketoacidosis, which requires IV insulin.

In post-marketing reports and clinical trials, no meaningful differences in immunogenicity (antibody formation) have been observed between Semglee and Lantus. That means both products have similar potential for causing antibody formation against insulin.

Storage, handling, and shelf-life

Proper storage and handling help maintain insulin potency.

  • Unopened vials and pens of both products should be refrigerated between 36 °F and 46 °F (2 °C to 8 °C). They should never be frozen and must be protected from direct heat and light.
  • In-use vials may be kept in the refrigerator or at room temperature (below 86 °F or 30 °C) for up to 28 days. After 28 days, any remaining insulin should be discarded, even if the vial still contains insulin.
  • In-use pens should be stored at room temperature only and should not be placed back in the refrigerator. Pens should never be stored with a needle attached. Each pen is designed for one patient only and must not be shared. After 28 days, the pen should be discarded.
  • Expired or improperly stored insulin should be thrown away. Using insulin that has been frozen or overheated can result in loss of potency and unpredictable blood sugar control.
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Bottom line

Semglee and Lantus both contain insulin glargine. Semglee was developed as a biosimilar to Lantus and proved through clinical trials that it offers the same glycemic control and safety profile. Their dosing, injection devices, formulation, and adverse effects are essentially interchangeable. Differences are primarily in manufacturing origin, branding, and pricing.

If you’re considering a switch between these insulins, the evidence shows that doing so does not compromise blood sugar control or safety. However, any change should be supervised by your healthcare provider to ensure proper dose adjustment and monitoring. Also note that the branded Semglee pen has been discontinued and is now only available in limited supply.

Frequently Asked Questions

Yes, Semglee is a biosimilar to Lantus (insulin glargine) and is considered interchangeable in many cases.

The generic name for Semglee is insulin glargine.

Semglee and Lantus are typically used on a unit-to-unit basis, meaning the dose is usually the same when switching.

Semglee is generally priced lower than Lantus, often offering significant savings depending on location, insurance coverage, and pharmacy pricing. At Pharma Giant, a 5-pen package of Semglee pen costs $99.95, while a 5-pen package of Lantus Solostar pen costs $177.

Both have similar effectiveness and safety profiles since Semglee is a biosimilar. The choice often depends on cost, availability, and patient preference.

Yes. Biocon discontinued Semglee vials and pens on December 31, 2025, but unbranded insulin glargine-yfgn (the authorized generic) remains available.

Alternatives include other long-acting insulins like Lantus, Basaglar, Toujeo, or Tresiba, depending on individual needs and medical advice.

Semglee provides long-acting glucose control, typically lasting up to about 24 hours after injection.

Related Articles

Sources

Blevins, T. C., Barve, A., Sun, B., & Ankersen, M. (2018). Efficacy and safety of MYL?1501D vs insulin glargine in patients with type 1 diabetes after 52?weeks: Results of the INSTRIDE 1 phase III study. Diabetes Obesity and Metabolism, 20(8), 1944–1950. https://doi.org/10.1111/dom.13322

Blevins, T. C., Barve, A., Sun, B., Raiter, Y., Aubonnet, P., Muniz, R., Athalye, S., & Ankersen, M. (2018). Efficacy and safety of MYL?1501D versus insulin glargine in patients with type 2 diabetes after 24 weeks: Results of the phase III INSTRIDE 2 study. Diabetes Obesity and Metabolism, 21(1), 129–135. https://doi.org/10.1111/dom.13495

Blevins, T. C., Barve, A., Raiter, Y., Aubonnet, P., Athalye, S., Sun, B., & Muniz, R. (2019). Efficacy and safety of MYL?1501D versus insulin glargine in people with type 1 diabetes mellitus: Results of the INSTRIDE 3 phase 3 switch study. Diabetes Obesity and Metabolism, 22(3), 365–372. https://doi.org/10.1111/dom.13904

Biosimilar Council. (2023). Semglee Launch Tracking. https://biosimilarscouncil.org/wp-content/uploads/2023/07/Biosimilars-Council-Semglee-Launch-Tracking-2023.pdf