Tresiba (Insulin Degludec): How This Long-Acting Insulin Works and When Telehealth Is Enough

Last updated: August 17, 2026

Tresiba is the brand name for insulin degludec, a long-acting (basal) insulin analog. Clinicians use it to improve blood sugar control in people 1 year of age and older with diabetes. People also search “Tresiba insulin,” “insulin degludec,” and “U-200 Tresiba.” Those names point to the same molecule. The pen concentration is not interchangeable with a syringe pulled from a FlexTouch pen. Tresiba is not a meal-time insulin, not an insulin pump cartridge, and not a treatment for diabetic ketoacidosis.

This guide covers how Tresiba is usually injected, how U-100 and U-200 pens differ, who should not use it, common side effects, and when a video visit is enough versus when you need labs or the ER. It is educational. It is not a diagnosis or a promise that any specific insulin will be prescribed.

Want a licensed clinician to review basal insulin or an A1C? Klarity Health has 2,000+ licensed providers. Many visits happen online. See online prescription options or browse conditions.

TLDR

• Insulin degludec (Tresiba) is a once-daily long-acting insulin for type 1 and type 2 diabetes. In type 1 diabetes it must be paired with a short-acting insulin. It is not recommended for diabetic ketoacidosis (MedlinePlus insulin degludec; DailyMed Tresiba).
• Mayo Clinic describes insulin degludec as a long-acting insulin that works slowly over about 24 hours. Inject it under the skin of the abdomen, upper arm, or thigh. Rotate sites. Do not inject into a vein or muscle (Mayo Clinic insulin degludec).
• DailyMed: adults may inject once daily at any time of day. Children inject once daily at the same time every day. Insulin-naive type 2 adults often start at 10 units once daily. Raise the dose no faster than every 3 to 4 days. Adults who miss a dose inject during waking hours and keep at least 8 hours between injections. Do not transfer Tresiba from a FlexTouch pen into a syringe.
• Tresiba comes as U-100 (1-unit clicks, up to 80 units) and U-200 (2-unit clicks, up to 160 units). The dose window already shows insulin units. Do not convert the number when you switch pens. Do not mix or dilute Tresiba. Do not use it in an insulin pump.
• Do not use Tresiba during a low-blood-sugar episode or if you are allergic to insulin degludec. Never share a pen or needle. Combining insulin with a TZD (pioglitazone, rosiglitazone) can cause fluid retention and heart failure.
• Typical home glucose targets many adults use: 80 to 130 mg/dL before meals and under 180 mg/dL two hours after a meal starts. A reading under 70 mg/dL is low (CDC manage blood sugar).
• Medicare covers many telehealth visits from home anywhere in the U.S. through December 31, 2027 (HHS telehealth policy). Seizure, loss of consciousness, chest pain, or blood sugar that will not come up is 911, not a video visit.

What Tresiba is trying to fix

Type 1 diabetes means the pancreas makes little or no insulin. Type 2 diabetes means the body resists insulin and often does not make enough of it. Glucose stays in the blood. Over years that raises the chance of heart disease, stroke, kidney disease, nerve damage, and eye disease. NIDDK notes some people with type 2 diabetes can control glucose with food, activity, sleep, and weight change. Many still need pills or insulin. Over time you may need more than one medicine (NIDDK insulin and medicines).

Insulin degludec replaces background insulin. MedlinePlus says it moves sugar from the blood into tissues and slows the liver from making more sugar. It does not cover the spike right after a meal. That is why type 1 regimens add a short-acting insulin at meals, and why some type 2 regimens still use meal-time insulin or an oral class.

Typical home targets the CDC lists for many adults:

• Before a meal: 80 to 130 mg/dL
• Two hours after the start of a meal: under 180 mg/dL

Blood sugar under 70 mg/dL is low. If you are sick and a reading is 240 mg/dL or higher, check ketones. High ketones can signal diabetic ketoacidosis, which is an emergency. Tresiba is not the insulin used to treat DKA.

Related Klarity guides: type 2 diabetes medication, SGLT2 inhibitors, sulfonylureas, DPP-4 inhibitors, TZDs, meal-time diabetes pills, colesevelam, and bromocriptine (Cycloset).

How Tresiba is usually taken

Tresiba is a clear, colorless solution injected under the skin. DailyMed and MedlinePlus adult directions:

• Once a day. Adults may inject at any time of day. Children inject at the same time every day.
• Sites: abdomen, upper arm, or thigh. Rotate within the same region. Skip areas of lipodystrophy or lumps.
• Insulin-naive type 2 adults: DailyMed lists 10 units once daily as a common start. The clinician then titrates using home glucose logs.
• Insulin-naive type 1: DailyMed lists about one-third to one-half of the total daily insulin as basal Tresiba, with the rest as short-acting insulin at meals. A common first total daily insulin estimate is 0.2 to 0.4 units per kilogram.
• Switching from another long- or intermediate-acting insulin: adults often start at the same unit dose. Children 1 year and older often start at 80% of the prior basal dose to lower hypoglycemia risk.
• Wait 3 to 4 days between dose increases.

U-100 FlexTouch pens deliver 1-unit steps up to 80 units. U-200 FlexTouch pens deliver 2-unit steps up to 160 units. The window already shows units. Do not convert. Children who need fewer than 5 units a day need the U-100 vial, not the pen.

Do not mix Tresiba with other insulin. Do not dilute it. Do not put it in a pump. Do not draw it out of a FlexTouch pen with a syringe. That last step can cause a severe overdose because the U-200 pen is twice as concentrated as U-100.

If an adult misses a dose, inject it during waking hours as soon as you remember, then keep at least 8 hours before the next injection. Do not double up. Pediatric missed doses need a call to the prescriber plus extra glucose checks. MedlinePlus uses the same 8-hour gap.

Unopened pens store in the refrigerator and must not freeze. Opened pens last up to 56 days at room temperature, away from heat and light. Use a new needle each time. Never share a pen.

Sources: Mayo Clinic insulin degludec; MedlinePlus insulin degludec; DailyMed Tresiba.

Who should not use Tresiba

DailyMed and Mayo Clinic flag these issues before a start or refill:

• Current hypoglycemia. Do not inject basal insulin into an active low.
• Allergy to insulin degludec or any Tresiba excipient.
• Diabetic ketoacidosis. Tresiba is not the treatment for DKA.
• Heart failure or low potassium. Insulin can worsen both. Combining insulin with a TZD can cause fluid retention.
• Kidney or liver disease. Insulin can last longer. The clinician may start lower and check glucose more often.

Bring a full list of prescriptions and supplements. Beta-blockers and some other drugs can hide the warning signs of a low. Alcohol can drop glucose. Niacin and many other medicines change insulin need. Tell the clinician before you start a new over-the-counter product.

Combination products that contain insulin degludec include Ryzodeg (with insulin aspart) and Xultophy (with liraglutide). Those are different prescriptions. Do not swap them for Tresiba on your own.

Side effects and warning signs

The most common problem is low blood sugar. DailyMed also lists injection-site reactions, lipodystrophy, itching, rash, swelling, and weight gain. Severe allergy, including anaphylaxis, can occur. Stop the insulin and get emergency care for hives all over, wheezing, or swelling of the face or throat.

Treat a low with a rapid sugar source you can absorb. Keep a glucagon kit if the clinician prescribed one, and make sure someone at home knows how to use it. Because Tresiba lasts a long time, recovery from a low can take longer than with a shorter basal insulin.

Call the same day, or use emergency care, for repeated lows, confusion, seizure, chest pain, sudden weight gain with swelling, or trouble breathing. Do not drive until you know how a new dose affects you.

When a telehealth visit is enough

A video visit can work when you already have a diabetes diagnosis, recent A1C and kidney labs, a current medication list, and home glucose logs (or CGM downloads). The clinician can decide whether basal insulin is the next step after metformin, an SGLT2 inhibitor, or another oral class, review U-100 versus U-200, and set a titration plan. Teaching a first injection often needs a live demo or a pharmacist. Ask for that if you have never used a pen.

Klarity Health offers online doctor visits with 2,000+ licensed providers. Many prescription questions can be handled without a clinic lobby. Coverage for a visit or a drug may vary by plan. Verify benefits before you book.

HHS notes that recent legislation extended many Medicare telehealth flexibilities through December 31, 2027, including visits from home without the old geographic limits.

Go to urgent or emergency care, not a routine video slot, if you have chest pain, a seizure, glucose that stays below 70 mg/dL after treatment, or ketones with vomiting.

Insurance, cost, and next steps

Tresiba is a branded basal insulin. Plans may prefer another long-acting insulin first. Prior authorization is common. A clinician cannot promise that your plan will pay. Ask the pharmacy about copay cards only after the prescriber confirms the product and the pen strength.

If overnight lows or morning highs make the dose hard to keep, say so. The fix is often a slower titration, a timing change, or a different basal insulin, not a doubled next dose.

Ready to talk through basal insulin with a licensed clinician? Check online prescription options or browse conditions we treat.

FAQ

Is Tresiba the same as Lantus or Basaglar?

No. Those are insulin glargine products. Tresiba is insulin degludec. Both are long-acting basal insulins, but the molecule, duration, pen strengths, and missed-dose rules differ. Do not substitute one for the other without a prescriber.

Can I take Tresiba at a different time each day?

Adults may inject once daily at any time of day, as long as at least 8 hours pass between doses. Children should inject at the same time every day. If a child misses a dose, call the prescriber.

What is the difference between Tresiba U-100 and U-200?

U-200 is twice as concentrated, so the same number of units fits in a smaller volume and the pen can deliver up to 160 units. The dose window still shows units. Never draw U-200 out of the pen with a U-100 syringe.

Can I get a Tresiba prescription online?

A licensed clinician can review your history, labs, and glucose logs on a video visit and decide whether Tresiba or another option is appropriate. They will not prescribe if DKA, missing labs, or an active low makes it unsafe. First-time pen teaching may need extra support. See online prescription care.

Disclaimer

This article is for education. It is not medical advice, a diagnosis, or a guarantee of insurance coverage. Coverage and prior authorization vary by plan. Confirm benefits before you book or fill a prescription. A licensed clinician must decide whether any medicine is right for you.