Semglee vs. Lantus: Differences and similarities explained

In this article:

• Key differences
• Conditions treated
• Are Semglee and Lantus interchangeable?
• Coverage and cost
• Side effects
• Drug interactions and warnings

In this article

• Key differences
• Conditions treated
• Are Semglee and Lantus interchangeable?
• Coverage and cost
• Side effects
• Drug interactions and warnings

Semglee and Lantus are two brand-name injectable medications used to treat both Type 1 and Type 2 diabetes. They both contain insulin glargine, a synthetic form of human insulin, which regulates blood sugar levels by helping the body maintain steady insulin levels throughout the day. Though these two insulins are highly similar, they differ slightly in chemical structure, as well as price and insurance coverage.

What are the main differences between Semglee and Lantus?

Semglee and Lantus are nearly identical biologics. They are both brand-name, long-acting insulin glargine available in multi-dose vials and single-use prefilled pens. Both are injected under the skin (subcutaneously) every day. 

However, these insulin products have slightly different chemical structures. Lantus is insulin glargine, whereas Semglee is insulin-glargine-yfgn. “Semglee is designed to be almost identical to Lantus, but they are derived from different organisms: One is created from bacteria, and the other is made from yeast,” says Troy Alexander-EL, MD, a board-certified internal medicine and primary care physician in Portland, Oregon.

They also have different average retail prices because Lantus came first — Semglee is an “interchangeable biosimilar” of Lantus.

Compare Semglee vs. Lantus key differences
	Semglee	Lantus
Drug class	Antidiabetic, long-acting insulin	Antidiabetic, long-acting insulin
Brand/generic status	Brand	Brand
What is the generic name? Or What is the brand name?	Insulin glargine-yfgn	Insulin glargine
What form(s) does the drug come in?	•10 mL vial or • 3 mL prefilled pen	• 10 mL vial or • 3 mL prefilled pen (called Lantus SoloStar)
What is the standard dosage?	Varies	Varies
How long is the typical treatment?	Long-term	Long-term
Who typically uses the medication?	Adult and pediatric patients with diabetes mellitus	Adult and pediatric patients with diabetes mellitus

 

Semglee vs. Lantus: Conditions treated

Both Semglee and Lantus are approved by the Food and Drug Administration (FDA)  for glucose management in people with either Type 1 or Type 2 diabetes.

Compare Semglee vs. Lantus conditions treated
Condition	Semglee	Lantus
Type 1 diabetes	Yes	Yes
Type 2 diabetes	Yes	Yes

 

Are Semglee and Lantus interchangeable?

The short answer: Yes, Semglee and Lantus are considered interchangeable. In fact, the FDA states that anyone prescribed Lantus is legally allowed to swap it for Semglee at the pharmacy without consulting their prescriber.

“Studies done to compare both Semglee and Lantus have shown that there is no meaningful difference in how they work, and how effective or safe they are,” says Cynthia Odogwu, MD, a Maryland-based, board-certified family medicine physician and founder of Kambili Health. 

Not all insulin products are interchangeable, but Semglee was approved in July 2021 as an interchangeable biosimilar drug to Lantus. Being a biosimilar isn’t quite the same as a generic drug. A biosimilar insulin product is very similar in structure to the reference product and is considered just as effective as the original. In this case, Lantus is an insulin glargine product, whereas Semglee is an insulin glargine-yfgn product.

Semglee vs. Lantus: Insurance coverage and cost comparison

Insurance coverage of Semglee and Lantus varies by health plan and can change from year to year. The best way to find out whether your plan covers Semglee or Lantus is to contact your insurance provider. Most plans do cover insulin, which is a critical treatment for people with diabetes, but some plans offer better coverage for certain insulin products over others. According to the  American Diabetes Association, most Medicare recipients can access free insulin, but exactly which insulin product is offered varies by state.

Patients paying the cash price for Semglee or Lantus can save on insulin by using SingleCare coupons. For instance, the average retail price of Lantus is $320 for 1, 10 mL of a 100-unit/mL vial. A free SingleCare card or coupon can lower the price to $65 for the same vial. Similarly, the average cost of Semglee is $110 per 1, 3 mL of a 100-unit/mL pen, but using a SingleCare coupon can lower that price to $20. 

Compare Semglee vs. Lantus cost and coverage
	Semglee	Lantus
Typically covered by insurance?	Yes, but coverage varies by plan.	Yes, but coverage varies by plan.
Typically covered by Medicare Part D?	Yes, but coverage varies by plan.	Yes, but coverage varies by plan.
Typically covered by Medicaid?	Yes, but coverage varies by state.	Yes, but coverage varies by state.
Quantity	1, 3 mL of 100 unit/mL pen	1, 10mL of 100 unit/mL vial
SingleCare cost	$20 at Kroger	$65 at Kroger

Prescription drug prices often change. These are the most accurate medication prices at the time of publishing in ZIP code 23666 as of 10/20/2025. The listed price without insurance references the price of brand-name drugs (unless otherwise specified). The listed SingleCare price references the price of generic drugs if available. Click the “SingleCare cost” link to see the latest drug prices.

Save on diabetes medication and supplies

Lantus vs. Semglee side effects

Remember, Lantus and Semglee are biosimilar drugs. “There is no difference in side effects between the medicines,” Dr. Odogwu says. Both can cause the following potential side effects:

• Hypoglycemia (low blood sugar)
• Weight gain
• Edema (fluid retention)
• Injection site reactions such as skin rash, redness, or itching

Hypoglycemia can become a very serious side effect if blood sugar levels are not stabilized quickly. People with diabetes and their caregivers need to know the early signs of low blood sugar, such as hunger and shakiness, as hypoglycemia can become life-threatening if blood glucose levels continue to drop.  

It’s essential to consult a healthcare provider for a list of complete side effects when starting Lantus, Semglee, or other insulin products.

Semglee and Lantus drug interactions and warnings

As interchangeable biosimilar insulin products, Semglee and Lantus come with the same lists of potential drug interactions and warnings. Specifically, both should be avoided by patients with an allergy to insulin glargine and a history of low blood sugar. Hypoglycemia is a serious risk for anyone using an insulin product, including long-acting insulin such as Semglee or Lantus. These diabetes treatments can also increase the risk of low potassium.

There are a few other warnings relevant to Semglee and Lantus:

• “Always let your healthcare provider know if you make changes to your diet and exercise habits, since these can affect your blood sugar and your insulin dose may need to be adjusted,” Dr. Odogwu says. 
• Never share needles, syringes, or insulin pens. 
• Never stop taking insulin without consulting your provider. “Taking insulin can sometimes cause weight gain and lead to people stopping their insulin,” Dr. Odogwu says. “Instead of stopping the medication, reach out to your physician to discuss a plan to manage the weight gain.”
• Avoid driving or operating heavy machinery until your body’s reaction to insulin stabilizes.

It’s important for patients to tell their prescribers if they are pregnant or breastfeeding before starting Semglee or Lantus. The healthcare professional may or may not decide to prescribe a different insulin product. 

Bottom line 

Only a healthcare provider familiar with your medical conditions, health history, and other medications can offer medical advice on which insulin product is best for you. The treatment of diabetes is a long-term process, so it is essential to establish care with a provider you trust. In the case of Semglee and Lantus, most providers will write a prescription for the lowest cost option. “Lantus was the only basal insulin that most doctors were taught, [so] it’s the first option in a lot of our minds. I will usually write for Lantus and place a note to change to the equivalent covered basal insulin if needed,” Dr. Alexander-EL says.