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

Insulin Glargine is one of the most prescribed medications in the United States — and one of the most important. Millions of Americans with Type 1 and Type 2 diabetes depend on it every single day to keep their blood sugar under control. Whether you've just been prescribed it for the first time or want to understand it better, this guide covers everything you need to know about Insulin Glargine in 2026.

What Is Insulin Glargine?

Insulin Glargine is a long-acting insulin analog — a modified, synthetic form of human insulin designed to mimic how the healthy pancreas releases a slow, steady trickle of insulin throughout the day and night. This steady background level is called basal insulin, and it's what prevents your blood sugar from rising between meals and overnight, even when you're not eating.

Unlike rapid-acting insulins (which are taken before meals to handle the glucose spike from food), Insulin Glargine is injected once daily and works continuously over approximately 24 hours. It has no pronounced peak — meaning blood levels are relatively flat and steady after injection, which reduces the risk of hypoglycemia compared to older insulin types.

Brand Names Available in 2026

Insulin Glargine is sold under several brand names in the United States in 2026:

• Lantus (U-100) — Sanofi: The original brand; approved in the U.S. in 2000; available as vials and SoloStar prefilled pens
• Toujeo (U-300) — Sanofi: A more concentrated version (300 units/mL vs. 100 units/mL); FDA-approved 2015; provides a longer, flatter action profile; available as SoloStar and Max SoloStar pens; indicated for adults and children ≥6 years
• Basaglar (U-100) — Eli Lilly: A follow-on product to Lantus; available as KwikPen; Tempo pen being discontinued end of 2026
• Rezvoglar (U-100) — Eli Lilly: FDA-interchangeable biosimilar to Lantus; approved December 2021
• Langlara (U-100) — Sunshine Lake Pharma/Lannett: Newest FDA-approved interchangeable biosimilar; approved May 4, 2026
• Generic Insulin Glargine (U-100): Available from Winthrop and others; often lowest cost option

What Is Insulin Glargine Used For?

FDA-approved indications include:

• Type 1 diabetes mellitus: Used in adults and children ≥6 years old to provide basal insulin coverage; must be combined with a short-acting (prandial) insulin taken before meals
• Type 2 diabetes mellitus: Used in adults to improve blood sugar control when oral medications and non-insulin injectables are not sufficient; often used alone as basal insulin or combined with oral antidiabetics or GLP-1 agonists

Not approved for: Diabetic ketoacidosis (DKA) — short-acting insulin is used for DKA. Not approved for Type 2 diabetes in children.

How Is Insulin Glargine Dosed?

Dosing is highly individualized. General starting points:

• Type 1 diabetes (insulin-naive adults and children): Approximately 0.2–0.4 units/kg/day as a starting total daily insulin dose; about 1/3 of that as basal insulin (Glargine), with the remaining 2/3 as short-acting prandial insulin
• Type 2 diabetes: Often started at 10 units/day and titrated up based on fasting blood glucose readings, with dose adjustments typically every 3–7 days

Insulin Glargine is injected once daily at the same time each day. It can be given at any time of day as long as you're consistent. Inject subcutaneously (just under the skin) into the abdomen, thigh, upper arm, or buttocks. Rotate injection sites to prevent lipodystrophy.

How to Use Insulin Glargine Correctly

1. Check that the solution is clear and colorless before each injection. Do not use cloudy, colored, or particulate insulin.
2. Never mix Insulin Glargine with other insulins in the same syringe.
3. Do not dilute Insulin Glargine.
4. Inject at the same time every day. Missing a dose can cause hyperglycemia.
5. Never share pens, cartridges, or syringes — sharing can transmit hepatitis, HIV, and other bloodborne infections.
6. Unopened insulin can be stored in the refrigerator (36–46°F) until the expiration date. Once opened, store at room temperature and use within 28 days for Lantus (or 56 days for Toujeo Max SoloStar).

Who Should NOT Use Insulin Glargine?

• Anyone currently experiencing hypoglycemia (low blood sugar) — do not inject until blood sugar is corrected
• Anyone with known hypersensitivity to insulin glargine or any excipients in the product
• It is not for use in treating diabetic ketoacidosis

For a deeper dive, see our post on how Insulin Glargine works and our guide to Insulin Glargine side effects.