insulin glargine
Lantus (insulin glargine) is a long-acting basal insulin from Sanofi. A single daily injection provides a steady, peakless insulin level for about 24 hours, controlling blood sugar in type 1 diabetes and in type 2 diabetes when other medicines are not enough.
This page is based on FDA prescribing information and the EMA medicine record for insulin glargine; the mechanism is explained in plain language, and analogies are used only where they stay accurate.
How it works
Explains what the medicine does in the body, not dosing, side effects, or safety.
An analogy
Think of insulin as the building manager who unlocks cells so glucose can come in. In diabetes the manager is missing or overwhelmed. Insulin glargine is a slow-release stand-in: injected once a day, it forms a small depot under the skin that trickles manager molecules out evenly around the clock, keeping the doors open without sudden rushes.
In simple terms
Insulin is the hormone that lets cells absorb glucose from the blood. People with type 1 diabetes make none, and many with type 2 diabetes eventually need extra. Insulin glargine is a modified human insulin designed to last about a day. Injected under the skin, it dissolves slowly and provides a constant background level, holding blood sugar steady between meals and through the night.
In depth
Insulin glargine differs from human insulin by an asparagine-for-glycine substitution at A21 and two arginine residues added to the B-chain C-terminus, shifting the isoelectric point so it remains soluble at acidic pH and precipitates in the neutral subcutaneous environment. The depot releases hexamers that dissociate slowly, giving a flat, peakless profile of roughly 24 hours. It provides basal coverage and is paired with rapid-acting insulin or other glucose-lowering agents.
See it in motion
A schematic animation of the mechanism — simplified for clarity, not drawn to scale.
How the A21 and B-chain changes give insulin glargine a flat 24-hour level
- Insulin glargine differs from human insulin by an asparagine-for-glycine substitution at A21 and two arginine residues added to the B-chain C-terminus, shifting the isoelectric point
- so it remains soluble at acidic pH and precipitates in the neutral subcutaneous environment.
- The depot releases hexamers that dissociate slowly, giving a flat, peakless profile of roughly 24 hours.
- Injected under the skin, it dissolves slowly and provides a constant background level, holding blood sugar steady between meals and through the night.
Target: Insulin receptor
The receptor through which insulin tells muscle, fat and liver cells to take up glucose; replacing basal insulin keeps glucose levels stable between meals and overnight.
Approved uses
Approved uses differ by country and change over time. Always follow your local prescribing information.
Approved uses in United States
FDA- To improve glycemic control in adults and pediatric patients with type 1 diabetes mellitus
- To improve glycemic control in adults with type 2 diabetes mellitus
Approved uses in European Union
EMA- Treatment of diabetes mellitus in adults, adolescents and children aged two years and above
Official sources
The statements on this page trace back to these records.
- Lantus (insulin glargine) — Summary of product characteristics and package leaflet, English version
European Medicines Agency
- U.S. Food and Drug Administration: insulin glargine prescribing information
U.S. Food and Drug Administration
- Emc SmPC: Insulin Glargine (UK licensed product)
Medicines and Healthcare products Regulatory Agency (EMC)
This page explains how the medicine works — it isn’t the patient leaflet. For anything that applies to you, read the leaflet that came with your medicine or ask your pharmacist.
MedUnfold provides educational content and is not medical advice. Always follow your local prescribing information and healthcare professional.