What Is Semglee?

Semglee (Insulin Glargine-yfgn) is a long-acting basal insulin used to improve blood sugar control in people with Type 1 and Type 2 diabetes.

Made by Mylan (a Viatris company), Semglee was the first insulin product to receive FDA approval as an interchangeable biosimilar — meaning it can be substituted for its reference product, Lantus, at the pharmacy without needing your doctor's approval in most states. It was first approved in 2020, with the interchangeable designation added in 2021.

Semglee is not a controlled substance. It's available as a pre-filled pen (100 units/mL in a 3 mL pen) and as a 10 mL vial (100 units/mL).

What Is Semglee Used For?

Semglee is FDA-approved to treat:

• Type 1 diabetes in adults and children aged 6 years and older
• Type 2 diabetes in adults

In both cases, Semglee provides "basal" insulin — a steady, low level of insulin that works in the background throughout the day and night. It's designed to keep blood sugar stable between meals and while you sleep.

For people with Type 1 diabetes, Semglee is always used alongside a rapid-acting mealtime insulin. For Type 2 diabetes, it may be used alone or combined with oral diabetes medications like Metformin, sulfonylureas, or GLP-1 receptor agonists.

How Is Semglee Taken?

Semglee is injected under the skin (subcutaneously) once daily at the same time each day. Here's what you need to know about taking it:

• Injection sites: Rotate between your abdomen, thigh, and upper arm. Don't inject in the same exact spot each time.
• Do not inject intravenously — Semglee is for subcutaneous injection only.
• Do not use in an insulin pump.
• Do not mix with other insulins in the same syringe or pen.
• Starting dose for Type 2 diabetes: Typically 10 units once daily, or 0.2 units per kilogram of body weight per day. Your doctor will adjust based on your blood sugar readings.
• Starting dose for Type 1 diabetes: Usually about one-third of your total daily insulin as basal insulin, with the rest coming from mealtime insulin.

Storage

• Unopened: Refrigerate (36°F to 46°F / 2°C to 8°C). Do not freeze.
• In use: Store at room temperature (up to 86°F / 30°C) and use within 28 days.

Who Should Not Take Semglee?

Semglee should not be used if you:

• Are allergic to Insulin Glargine or any of its ingredients
• Are currently experiencing a hypoglycemic episode (low blood sugar)

Tell your doctor before starting Semglee if you have:

• Kidney or liver problems (dose adjustments may be needed)
• Heart failure concerns, especially if taking thiazolidinediones
• A history of severe allergic reactions to insulin

For more on potential risks, see our guide on Semglee side effects and drug interactions.

How Much Does Semglee Cost?

Without insurance, Semglee typically costs between $125 and $350 per box of 5 pens or per vial, depending on the pharmacy. While that's generally less expensive than brand-name Lantus, it's still a significant cost for many patients.

Here are ways to lower the cost:

• Viatris savings card: Commercially insured patients may be eligible for copays as low as $0–$35 per prescription. Visit semglee.com to enroll.
• Discount cards: Services like GoodRx, SingleCare, and RxSaver can bring the cash price down to $80–$150 in some cases.
• Insurance: Most commercial and Medicare Part D plans cover Semglee, often at a preferred formulary tier. Check with your plan for exact copay details.
• Patient assistance: The Viatris Patient Assistance Program provides Semglee at no cost to qualifying uninsured or underinsured patients.

For a complete breakdown, see our guide on how to save money on Semglee.

Semglee vs. Lantus: What's the Difference?

Semglee and Lantus contain the same active ingredient (Insulin Glargine) and work the same way. The key differences are:

• Price: Semglee is generally less expensive than Lantus.
• Manufacturer: Semglee is made by Mylan/Viatris; Lantus is made by Sanofi.
• Interchangeability: Semglee's FDA interchangeable designation means pharmacists can substitute it for Lantus without contacting the prescriber.

Both have the same mechanism of action, side effect profile, and clinical effectiveness.

Final Thoughts

Semglee is a safe, effective, and often more affordable option for managing diabetes with basal insulin. As the first interchangeable biosimilar insulin in the U.S., it gives patients and pharmacists more flexibility.

If you're having trouble finding Semglee at your pharmacy, Medfinder can help you check stock near you. And if you need a prescriber, here's how to find a doctor who can prescribe Semglee.