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

Tresiba is a prescription insulin used every day by hundreds of thousands of people with diabetes across the United States. If you've just been prescribed Tresiba or are considering it, you probably have questions: What exactly is it? How does it work? How do you take it? And is it right for you?

This guide covers everything a patient needs to know about Tresiba in plain English — no medical jargon, just clear facts.

What Is Tresiba?

Tresiba is the brand name for insulin degludec, an ultra-long-acting basal insulin analog manufactured by Novo Nordisk. It was FDA-approved on September 25, 2015, and has been available in US pharmacies since January 2016. It is included on the World Health Organization's List of Essential Medicines.

"Basal" insulin means it works in the background — it provides a steady, low-level supply of insulin throughout the day and night to keep your blood sugar stable between meals and while you sleep. Tresiba is not a mealtime insulin and does not provide the quick burst of insulin needed after eating. Many people with diabetes take both a basal insulin (like Tresiba) and a rapid-acting mealtime insulin as part of a complete regimen.

What Is Tresiba Used For?

Tresiba is FDA-approved to improve glycemic control (blood sugar management) in:

Adults with type 1 diabetes (used with a mealtime insulin)

Adults with type 2 diabetes (used alone or with other diabetes medications)

Children aged 1 year and older with type 1 or type 2 diabetes

Tresiba is NOT for: Treating diabetic ketoacidosis (DKA), use in an insulin pump, or intravenous administration.

What Makes Tresiba Different from Other Basal Insulins?

Tresiba stands out from other long-acting insulins for two key reasons:

Ultra-long duration (42+ hours): Most long-acting insulins last 18-24 hours. Tresiba lasts over 42 hours — the longest of any currently marketed insulin. This means even if you occasionally miss a dose or take it a few hours late, the insulin remains active.

No peak: Tresiba has no pronounced activity peak. It provides a flat, steady glucose-lowering effect throughout the day. The DEVOTE trial showed this reduces severe hypoglycemia risk by 40% vs. insulin glargine in type 2 diabetes patients. Fewer nighttime lows is a key benefit for many patients.

Available Forms and Strengths

FlexTouch U-100 pen (100 units/mL): 3 mL per pen, sold in boxes of 5 pens. Doses from 1 to 80 units in 1-unit increments.

FlexTouch U-200 pen (200 units/mL): 3 mL per pen, sold in boxes of 3 pens. Doses from 2 to 160 units in 2-unit increments. Good for patients who need higher doses.

Vial U-100 (100 units/mL): 10 mL vial for use with a U-100 insulin syringe. Used for children requiring less than 5 units/day or patients who prefer syringes.

How to Take Tresiba

Once daily: Inject under the skin (subcutaneously) once per day. You can take it at any time of day, as long as at least 8 hours have passed since your last dose.

Flexible timing: Unlike some insulins that must be taken at the exact same time each day, Tresiba's ultra-long duration allows some flexibility. Consistency is still preferred, but if you miss your usual time by a few hours, just take it as soon as you remember.

Injection sites: Abdomen (at least 2 inches from navel), outer thighs, or outer back of upper arms. Rotate sites at every injection.

Storage: Unopened pens and vials: refrigerator until expiration, OR room temperature (below 86°F/30°C) for up to 56 days. Do not freeze.

Typical Starting Doses

Type 1 diabetes (insulin-naive): 30-50% of total daily insulin dose once daily

Type 2 diabetes (insulin-naive): 10 units once daily

Switching from another basal insulin: Adults: same unit dose as your current basal insulin. Children: 80% of the current dose.

Your doctor will tailor your dose based on your blood sugar readings and will adjust over time. Never change your insulin dose without consulting your healthcare provider.

Availability and Finding Tresiba in Stock

Tresiba has experienced intermittent supply shortages in 2025-2026. If you can't find it at your usual pharmacy, medfinder can help you find which pharmacies near you have it in stock. It checks multiple pharmacies at once and texts you the results, saving you hours of calling around.

To learn more about side effects, see: Tresiba Side Effects: What to Expect and When to Call Your Doctor.