Insulin Glargine
Injection (pen)
Quick Summary
Insulin glargine releases insulin slowly over about 24 hours, providing a steady background level.
Medical Uses
How it's taken
Injected under the skin once a day at the same time. Rotate injection sites. Your doctor adjusts the amount based on sugar readings.
Your doctor decides the right dose for you and how long to take it.
Your doctor decides the right dose for you. Follow their instructions and the label.
Common Side Effects
Low blood sugar
The most common side effect.
Injection site lumps
Rotate sites.
Weight gain
Sometimes.
Interactions
Alcohol
Increases low sugar risk.
Steroids
Raise blood sugar.
Critical Warnings
Low blood sugar
Black Box Warning: Shaking, sweating, confusion: take sugar straight away. Tell your doctor if it happens.
Storage
Keep unopened pens in the fridge; don't freeze.
Sources and further reading
Last updated 21 October 2026. For more detail, see these trusted health organisations.
- Insulin Glargine (rDNA origin) Injection: drug information(opens in a new tab) · MedlinePlus, US National Library of Medicine
- Insulin(opens in a new tab) · NHS