What Is Insulin Glargine-Yfgn? Uses, Dosage, and What You Need to Know in 2026

Insulin glargine-yfgn is a long-acting basal insulin used to help control blood sugar in people with Type 1 and Type 2 diabetes. Originally marketed under the brand name Semglee (discontinued December 31, 2025), it remains available in 2026 as an unbranded generic through manufacturers including Civica Rx. This comprehensive guide covers everything you need to know about this medication.

What Is Insulin Glargine-Yfgn?

Insulin glargine-yfgn is a biosimilar, long-acting insulin analog — a synthetic form of insulin made using recombinant DNA technology. The 'yfgn' suffix identifies it as a distinct biosimilar product, per FDA naming conventions. It was approved on July 28, 2021 as the first interchangeable biosimilar insulin in US history.

It is biosimilar to and interchangeable with Lantus (insulin glargine) — the widely used long-acting insulin made by Sanofi. 'Interchangeable' means the FDA determined it can be substituted for Lantus at the pharmacy level without prescriber intervention, just as a generic drug is substituted for a brand-name drug.

FDA-Approved Uses

Insulin glargine-yfgn is FDA-approved to improve glycemic control in:

Adults with Type 1 diabetes mellitus

Pediatric patients ages 6 and older with Type 1 diabetes mellitus

Adults with Type 2 diabetes mellitus

It is

not recommended for the treatment of diabetic ketoacidosis (DKA), which is a medical emergency requiring rapid-acting insulin given intravenously. It has not been established as safe or effective in children younger than 6 years of age or in children with Type 2 diabetes.

What Forms and Strengths Is It Available In?

10 mL multiple-dose vials: 100 units/mL (U-100). Used with syringes for injection.

3 mL single-patient-use prefilled pens: 100 units/mL (U-100). Dials in 1-unit increments. Needles not included.

Important: Do NOT mix or dilute insulin glargine-yfgn with any other insulin or solution. Do NOT administer via an insulin pump or intravenously.

How to Take Insulin Glargine-Yfgn

Route: Subcutaneous injection only (under the skin)

Frequency: Once daily, at the same time each day

Injection sites: Abdomen (stomach area), thigh, or upper arm (deltoid). Rotate sites with each injection.

When: Any time of day is acceptable, as long as it is the same time daily. Some patients take it at bedtime to minimize nocturnal hypoglycemia risk.

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Dosage: How Much Should I Take?

Dosage is highly individualized and must be determined by your healthcare provider based on your blood glucose monitoring results, metabolic needs, type of diabetes, and other medications. There is no standard dose — your doctor will start at an estimated dose and adjust over time.

If switching from a different long-acting insulin (e.g., NPH or Toujeo 300 units/mL), dosage adjustments may be needed:

From once-daily insulin glargine 300 units/mL: start at 80% of the previous dose

From once-daily NPH insulin: use the same dose as NPH

From twice-daily NPH insulin: start at 80% of the total daily NPH dose

Storage Instructions

Unopened: Store in refrigerator (36°F–46°F / 2°C–8°C). Do not freeze. Protect from heat and light.

In-use vials: Can be stored in the refrigerator or at room temperature below 86°F (30°C). Check label for in-use expiration date.

In-use pens: Do not refrigerate in-use pens. Store at room temperature below 86°F. Check label for in-use expiration.

Want to understand how insulin glargine-yfgn works in the body? Read our full explanation: How Does Insulin Glargine-Yfgn Work? Mechanism of Action Explained. And if you need help finding it in stock near you, medfinder contacts pharmacies on your behalf.