An ultra-long-acting (basal) insulin
Insulin degludec
An ultra-long-acting (basal) insulin giving very steady background cover, taken once a day.
What is Insulin degludec?
Insulin degludec is an ultra-long-acting insulin that gives very steady background (basal) cover, helping keep blood glucose stable between meals and overnight. It is injected under the skin once a day, and because it lasts a long time it can be given with some flexibility in timing if needed. In type 1 diabetes it is used with a separate mealtime insulin. Its main risk, like all insulin, is a hypo, so it is important to recognise and treat the warning signs. Always rotate injection sites and never share your pen or needles.
Education and reference only. This is a plain-language guide to Insulin degludec — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Insulin degludec is an ultra-long-acting insulin analogue used as the background, or basal, part of insulin treatment in type 1 and type 2 diabetes. After injection it forms a depot under the skin that releases very slowly, giving an exceptionally long and flat effect that lasts well beyond a day. This makes its cover very steady and allows some flexibility in the timing of the daily injection. In type 1 diabetes it is paired with a fast-acting mealtime insulin, and it comes in prefilled pens and cartridges, including a more concentrated version.
How it works
Insulin lets glucose pass from the blood into the cells and tells the liver to stop making extra glucose. In diabetes too little insulin is made or it works poorly, so glucose rises. Degludec replaces the slow background insulin a healthy pancreas would release; after injection it forms a steady depot that releases over a very long time, giving a flat, consistent effect. Because it builds up to a stable level and lasts so long, its background cover is smooth and the timing of the daily dose can be a little flexible.
Company & origin
Originated / developed by: Novo Nordisk.
An ultra-long-acting insulin analogue developed by Novo Nordisk, used in the UK as a once-daily background insulin with a very long and steady duration of action.
What it treats
Conditions Insulin degludec is used for
Practical use
How to take Insulin degludec
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Inject under the skin once a day, ideally at about the same time, into the tummy, thigh, buttock or upper arm.
- If a dose timing needs to shift, leave a sensible gap between injections and follow your team's advice on flexibility.
- Rotate your injection site within an area each time to prevent lumpy or hardened skin that changes absorption.
- Use a new needle each time, do not shake the pen, and never share a pen or needle with anyone else.
- Recognise hypo warning signs and always carry fast-acting sugar such as glucose tablets or a sugary drink.
- On sick days keep taking your insulin, check your blood glucose more often and follow your sick-day plan.
Weighing it up
Advantages & disadvantages of Insulin degludec
Advantages
- Very long, flat action gives smooth background cover with a single daily injection.
- Allows some flexibility in injection timing because it lasts so long.
- Often associated with fewer overnight lows because of its steady, peakless profile.
Disadvantages
- Like all insulin it can cause hypoglycaemia, which needs prompt treatment and ongoing awareness.
- It only covers background needs, so a separate mealtime insulin is still required in type 1 diabetes.
- The concentrated version is not interchangeable unit-for-unit with the standard strength, which can cause confusion.
Practical use
Good to know
Degludec is a background insulin, not a mealtime one, so it does not cover the rise after eating. Its very long action makes its cover smooth and means that, if a day's injection is earlier or later than usual, this is usually less disruptive than with shorter basal insulins, though you should keep to a regular routine and follow your team's advice. The key safety point is hypoglycaemia: warning signs include shakiness, sweating, hunger, a fast heartbeat and confusion, treated with fast-acting sugar then a snack. Inject under the skin, rotate sites to avoid lumpy skin, and never share a pen or needle. The more concentrated version is not interchangeable unit-for-unit with the standard strength. On sick days keep taking your insulin and follow your sick-day plan.
Who should not take it / use with caution
- It must not be used during an episode of low blood glucose (hypoglycaemia).
- People with a known allergy to insulin degludec or its ingredients should not use it.
- It is not suitable on its own for diabetic ketoacidosis, which needs urgent hospital treatment with fast-acting insulin.
Monitoring
- Regular blood glucose checks, and HbA1c over time, to guide the background insulin amount.
- Reviewing injection sites for lumps or hardened skin that can affect absorption.
- Watching the frequency and pattern of hypos, especially overnight, to adjust treatment.
Side effects
- Hypoglycaemia (low blood glucose) is the most important side effect, with shakiness, sweating, hunger and confusion.
- Redness, itching or lumpy, hardened skin at injection sites if sites are not rotated.
- Weight gain and, rarely, allergic reactions or swelling.
Key interactions
- Other glucose-lowering medicines, alcohol and some painkillers can increase the risk of a hypo.
- Steroids, some diuretics and certain other medicines can raise blood glucose and reduce insulin's effect.
- Beta-blockers can mask the warning signs of a hypo, so extra glucose monitoring may be needed.
Available as: Solution for injection under the skin, in prefilled pens and cartridges, in standard and concentrated strengths.
Answers
Insulin degludec: frequently asked questions
What makes insulin degludec different from other background insulins?
It is ultra-long-acting with a very flat, steady effect lasting well beyond a day, which gives smooth cover and some flexibility in injection timing.
Is it a mealtime insulin?
No. It is a background (basal) insulin; in type 1 diabetes you also need a separate fast-acting insulin for meals.
How do I treat a hypo on degludec?
Treat it straight away with fast-acting sugar such as glucose tablets or a sugary drink, then a snack, and always carry sugar with you.
Can the timing of my injection vary?
Because it lasts so long, some flexibility is possible, but you should still aim for a regular routine and follow your team's advice.
Can I share my insulin pen?
No. Pens and needles must never be shared, even with a new needle, because of the risk of passing on infection.
The wider class
About Insulin
Insulin degludec belongs to the insulin class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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