Medicines
Insulin degludec
Insulin degludec is a background (basal) insulin that lasts more than 24 hours. It is usually injected once a day.
- Type of medicine
- Ultra long-acting insulin
- Also known as
- Tresiba, Xultophy (with liraglutide)
- Comes as
- injection pens
- How you get it
- Prescription only
What it is used for
- Type 1 diabetes, as background insulin
- Type 2 diabetes, when other treatments are not enough
Read our guides:
Off-label uses
Doctors sometimes prescribe a medicine for a condition it is not officially licensed for. This is called off-label use. It is legal and common when there is good evidence it helps, and your doctor should explain why they are suggesting it.
Insulin degludec is not commonly used off-label.
How it works
Insulin degludec forms a store under the skin that releases insulin slowly and steadily for more than 24 hours. This keeps blood sugar stable between meals and overnight.
Side effects
Like all medicines, Insulin degludec can cause side effects, although not everyone gets them. Many are mild and ease after the first few weeks.
Common side effects
- low blood sugar (hypos)
- redness or swelling where you inject
- lumps under the skin
- weight gain
Tell your doctor or pharmacist if these bother you or do not go away.
Serious side effects
These are rare. Call 111 or contact your doctor straight away if you get:
- a severe hypo with confusion, fits or passing out
- swelling of the face or trouble breathing
Call 999 if you have signs of a serious allergic reaction, such as swelling of your lips, mouth, throat or tongue, or trouble breathing.
You can report any side effect to the Yellow Card scheme, run by the medicines regulator.
Stopping and withdrawal
Important safety information
- It comes in two strengths (100 and 200 units per ml). Check you have the right one.
- Rotate injection sites.
Questions about your medicine?
A pharmacist can answer questions about your medicines for free, without an appointment. You can also ask your GP for a medication review. Check if you can get free prescriptions.
Official information
Last checked 5 October 2026. Tell us if something looks wrong.
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