Insulin Detemir (Levemir)

At a glance

• Class: Long-acting (basal) insulin analogue
• Brand name: Levemir®
• Drug name: Insulin detemir
• Route: Subcutaneous injection (pre-filled pens or cartridges)
• Indication: Diabetes mellitus (type 1 and type 2) in adults and children ≥1 year
• Key point (UK 2025): Levemir is being discontinued by the end of 2026; no new initiations – patients need planned switching to alternative basal insulin.

What is Levemir? 🧬

Levemir is a long-acting insulin analogue used as the basal insulin in multiple daily injection (MDI) regimens or in combination with oral agents/GLP-1 agonists. Chemically, insulin detemir is a human insulin molecule that has been acylated (a fatty acid side chain is attached) at the B29 lysine residue. This modification increases self-association in the subcutaneous tissue and promotes reversible binding to albumin in the bloodstream. These two mechanisms slow absorption and prolong its action, giving a relatively “flat” profile suitable for background insulin replacement.

How does Levemir work? ⏱

• After injection: Insulin detemir forms hexamers and associates in the SC depot, delaying absorption.
• Albumin binding: Once absorbed, it binds extensively to albumin in the plasma and interstitial fluid. Only the unbound fraction is pharmacologically active, which smooths peaks and prolongs duration.
• Duration: Typically around 12–24 hours; in real life many adults (especially with type 1) need twice-daily dosing for full 24-hour cover.
• Glucose effect: Reduces hepatic glucose output, promotes peripheral glucose uptake and suppresses lipolysis, mimicking physiological basal insulin secretion.

When do we use Levemir? (And why it’s changing in the UK) 🇬🇧

Traditional indications

• Type 1 diabetes – as the basal component of a basal–bolus regimen (e.g. Levemir + rapid-acting insulin at meals).
• Type 2 diabetes – as add-on therapy when oral agents ± GLP-1 agonists are insufficient, usually once or twice daily.
• Children and adolescents – widely used historically due to predictable profile and perceived lower risk of nocturnal hypoglycaemia compared with some alternatives.

Current UK position (2025 onwards)

• Novo Nordisk has decided to stop manufacturing Levemir globally (pens and cartridges).
• In the UK, national Medicines Supply Notifications advise:
  • Do not start new patients on Levemir.
  • Plan a phased switch of existing patients to alternative basal insulins (e.g. NPH, insulin glargine, insulin degludec) according to local guidelines and specialist advice.
  • Supplies are expected to be available only until around December 2026.
• Many local formularies already discourage Levemir in type 2 diabetes due to cost and the availability of once-daily basal analogues with longer duration.

Practical teaching point: On the ward or in clinic, if you see a patient on Levemir, you should think “basal insulin analogue that is being phased out – what’s the plan for switching?” and check their diabetes notes or write to the GP/diabetes team.

Dosing and regimens 💉

General principles

• Dose is always individualised based on blood glucose profiles, HbA1c, hypoglycaemia risk and body weight.
• Insulin detemir “units” are equivalent to units of human insulin (1 unit detemir ≈ 1 unit human insulin in potency).
• Given by subcutaneous injection in abdomen, thigh, upper arm or buttock – rotate sites to reduce lipohypertrophy.

Common patterns

• Type 1 diabetes (basal–bolus):
  • Often given twice daily (e.g. morning and bedtime) to cover 24 hours.
  • Starting total daily insulin dose is usually ~0.5–0.7 units/kg/day (all insulins), split roughly 40–50% basal and 50–60% bolus – then titrated.
• Type 2 diabetes (add-on to tablets/GLP-1 RA):
  • Typical starting basal dose is around 10 units once daily or 0.1–0.2 units/kg, usually in the evening.
  • Dose is increased by small increments (e.g. 2–4 units every 3–4 days) based on fasting glucose and hypoglycaemia risk.

Remember: These are teaching ranges only – always follow local protocols and titration charts for real patients.

Pharmacology and PK highlights

• Onset: Around 1–2 hours.
• Peak: Relatively “peak-less” compared to NPH, but some patients still report modest peaks.
• Duration: About 12–24 hours, dose-dependent – larger doses last longer.
• Variability: Lower day-to-day variability compared with NPH insulin, which contributes to fewer symptomatic hypos for some patients.
• Metabolism: Broken down by proteolytic enzymes in liver and kidney, like endogenous insulin.

Pros and cons ⚖️

Advantages

• Flatter and more predictable profile than NPH insulin.
• Lower risk of nocturnal hypoglycaemia compared with NPH in many studies.
• Flexible dosing – once or twice daily depending on patient need.
• Extensive clinical experience, including in children ≥1 year and pregnancy (when used under specialist supervision).

Disadvantages

• Shorter duration than some other basal analogues (e.g. insulin degludec, insulin glargine U300), so often needs twice-daily administration.
• Generally more expensive than NPH and some glargine biosimilars, which has driven formulary shifts.
• Being discontinued – patients on Levemir must be switched to alternatives before supplies run out.

Adverse effects and safety 🚨

• Hypoglycaemia – the main risk; episodes may be less frequent and milder than with NPH, but still a major safety issue. Teach patients “4 is the floor” (BG <4 mmol/L = hypo).
• Weight gain – all insulins can cause weight gain; detemir may be slightly more weight-neutral than some others, but the effect is modest and not a reason to favour it now that it is being withdrawn.
• Injection site reactions – pain, redness, or swelling. Lipohypertrophy with repeated injections at the same spot.
• Allergy – true insulin allergy is rare but possible (local or systemic).
• Driving and DVLA: As with all insulins, patients must monitor glucose, be aware of hypoglycaemia symptoms, and follow DVLA guidance for group 1 and 2 licences.

Special situations

Elderly and frail patients

• Lower insulin requirements; higher risk of hypos and falls.
• Targets often relaxed (e.g. HbA1c >58 mmol/mol) in those with significant frailty or limited life expectancy.
• Switching off Levemir needs careful planning with simple regimens and clear community support.

Renal and hepatic impairment

• Reduced insulin clearance ⟶ lower dose requirements.
• Frequent glucose monitoring and gradual titration are crucial, especially when switching to another basal analogue.

Peri-operative care

• Standard practice is to reduce the basal dose (often ~50–80% of usual) the night before or morning of surgery, with close capillary glucose monitoring.
• Local peri-operative diabetes protocols should be followed; the principles apply similarly to other basal insulins once the patient has switched.

2025–26: Levemir withdrawal – switching to alternatives 🔄

Because Levemir is being discontinued, the key clinical question is no longer “Should I start Levemir?” but “How do I safely switch this patient to another basal insulin?”.

Key UK messages

• No new initiations of Levemir.
• Identify patients currently on Levemir (type 1 and type 2, including children and pregnant women).
• Plan a switch to another basal insulin (e.g. NPH, insulin glargine, insulin degludec) using:
  • Local diabetes formularies and switching guidelines.
  • Joint guidance from specialist societies (e.g. ABCD and PCDO Society).
  • Individualised dose conversions – often starting with a similar or slightly reduced basal dose, then titrating based on glucose readings.
• Communicate clearly with patients (letters, clinic conversations, education on the new device and hypo management).
• Be especially careful in high-risk groups – those with recurrent hypos, hypo unawareness, frailty, visual/dexterity impairment, or pregnancy.

Teaching angle: In exams and on the ward, you can still describe Levemir as a long-acting basal insulin analogue, but in UK practice questions it’s now high-yield to mention that it is being phased out and that clinicians should follow national/local guidance for switching to alternative basal insulins.

Quick comparison: Levemir vs other basal insulins

Key take-home points for students and juniors 🎓

• Levemir = insulin detemir, a long-acting basal insulin analogue that works via self-association and albumin binding.
• Used as the basal component of insulin regimens in type 1 and type 2 diabetes, historically popular in children and young adults.
• Given once or twice daily, titrated against fasting and pre-meal blood glucose, with standard insulin risks (especially hypoglycaemia).
• UK 2025+: Levemir is being phased out globally; no new starts and all existing patients should be planned for switching to alternative basal insulins before end of 2026.
• On the ward or in clinic, always check for: hypo history, injection technique, lipohypertrophy, driving safety, and the plan for transition to a new basal insulin.