Insulin glargine

Long-acting insulin analogue

ATC code: A10AE04

Brand names: Lantus, Basaglar, Semglee

Updated 23 Sep 2026 · Methodology

Indications

Insulin-dependent type 2 diabetes mellitus

First line

In type 2 diabetes, basal insulin is added when non-insulin therapy stops holding target, symptoms of decompensation appear or hyperglycaemia is marked. Glargine suits that role with one injection a day. Spain's redGDPS and the advise starting low and titrating to fasting glucose while metformin continues. Hypoglycaemia risk rises noticeably if a sulfonylurea stays in the regimen: the AEMPS Lantus label lists oral antidiabetic drugs among agents that potentiate insulin, and the secretagogue dose is then revisited. The second risk factor is ACE inhibitors, named in the same label section. When basal insulin starts, self-monitoring is stepped up rather than left as it was.

Sources

ICD-10: E11.9 · ICD-11: 5A11

Type 1 diabetes mellitus

First line

Insulin glargine is the basal component of a type 1 diabetes regimen: it holds the background between meals and overnight, while a rapid insulin covers food. The AEMPS Lantus label allows the product from 2 years of age. Against NPH, glargine produces fewer nocturnal hypoglycaemic episodes at comparable , and that is its main practical difference. One injection a day at the same time, rotating sites within one anatomical area. The dose is titrated to fasting glucose rather than to a single reading: basal insulin answers for the background, not for post-meal rises. Switching from NPH to glargine, and switching between the 100 and 300 units/ml strengths, calls for dose recalculation and tighter self-monitoring in the first weeks.

Sources

ICD-10: E10 · ICD-11: 5A10

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

Muscle mass gain (bodybuilding self-use)

Not recommended

In gym regimens insulin glargine is used as a background between shots of rapid insulin, on the expectation of an anabolic effect and amino acid transport into muscle. No regulator has approved that use in Spain or Russia, and there are no clinical studies of muscle gain in people without diabetes. The danger is not theoretical: in a person without diabetes an eyeballed dose drops glucose hours after the injection, and the long action of glargine stretches hypoglycaemia across the night and the second half of the day. Severe hypoglycaemia in athletes has ended in seizures, coma and death. Loading with sugar does not protect: the glucose rise is shorter than the drug's action. If insulin has been suggested for building mass, consider seeking a second opinion from an endocrinologist.

Sources

AEMPS: Ficha técnica Lantus SoloStar 100 unidades/ml solución inyectable (2026)

How to read tiers A–F

AStrong evidence – first or second line in international guidelines
BRecommended in selected cases
CStudy data contradict each other
DBenefit not proven, no documented harm
FDocumented harm, or risk without benefit

Mechanism of action

Glargine differs from human insulin by two arginines at the end of the B chain and by asparagine replaced with glycine in the A chain. The molecule therefore stays soluble in the acidic pen solution and precipitates as microcrystals in the neutral subcutaneous tissue. The crystals dissolve slowly and insulin enters the blood as a steady flow without a marked peak for about 24 hours. At the receptor glargine behaves like ordinary insulin: it drives glucose uptake into muscle and fat and suppresses gluconeogenesis and lipolysis. The 300 units/ml strength gives an even flatter profile than 100 units/ml, and units of the two strengths are not interchangeable.

Safety

Contraindications

Hypoglycaemia
Hypersensitivity to insulin or to any excipient of the product

Serious adverse effects

Severe hypoglycaemia with loss of consciousness and seizures
Hypokalaemia in overdose, up to rhythm disturbance
Anaphylaxis and generalised insulin allergy
Oedema and decompensated heart failure when combined with pioglitazone

Common adverse effects

Hypoglycaemia: sweating, tremor, palpitations, hunger, confusion
Injection site reactions: redness, swelling, itching
Lipohypertrophy when injections stay in one spot
Weight gain early in treatment

Pregnancy: can you take Insulin glargine?

Insulin does not cross the placenta and remains the mainstay of glycaemic control in pregnancy. Requirements shift by trimester: usually lower in the first, rising from the second, and falling sharply after delivery. The dose is revisited at every stage.

Breastfeeding: can you take Insulin glargine?

The label sets no restriction during breastfeeding: insulin is broken down in the infant's gut and does not reach the bloodstream. Insulin requirements often fall during lactation, so the dose is retitrated.

Calculate RID

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Label mentions14 mentions

Verbatim lines from the interaction sections, in the language of the label

From this drug’s label

antidiabéticos oralesclass named in the label
«Entre las sustancias que pueden aumentar el efecto hipoglucemiante e incrementar la susceptibilidad a la hipoglucemia se cuentan los medicamentos antidiabéticos orales, los inhibidores de la enzima…»
AEMPS, section 4.5 · Open on CIMA
antipsicóticosclass named in the label
«Entre las sustancias que pueden reducir el efecto hipoglucemiante se incluyen los corticosteroides, el danazol, el diazóxido, los diuréticos, el glucagón, la isoniazida, los estrógenos y los…»
AEMPS, section 4.5 · Open on CIMA
betabloqueantesclass named in the label
«Los betabloqueantes, la clonidina, las sales de litio o el alcohol pueden potenciar o debilitar el efecto hipoglucemiante de la insulina. La pentamidina puede provocar hipoglucemia, que algunas veces…»
AEMPS, section 4.5 · Open on CIMA
Clonidine
«Los betabloqueantes, la clonidina, las sales de litio o el alcohol pueden potenciar o debilitar el efecto hipoglucemiante de la insulina. La pentamidina puede provocar hipoglucemia, que algunas veces…»
AEMPS, section 4.5 · Open on CIMA
Clozapine
«Entre las sustancias que pueden reducir el efecto hipoglucemiante se incluyen los corticosteroides, el danazol, el diazóxido, los diuréticos, el glucagón, la isoniazida, los estrógenos y los…»
AEMPS, section 4.5 · Open on CIMA
corticosteroidesclass named in the label
«Entre las sustancias que pueden reducir el efecto hipoglucemiante se incluyen los corticosteroides, el danazol, el diazóxido, los diuréticos, el glucagón, la isoniazida, los estrógenos y los…»
AEMPS, section 4.5 · Open on CIMA
Disopyramide
«Entre las sustancias que pueden aumentar el efecto hipoglucemiante e incrementar la susceptibilidad a la hipoglucemia se cuentan los medicamentos antidiabéticos orales, los inhibidores de la enzima…»
AEMPS, section 4.5 · Open on CIMA
diuréticosclass named in the label
«Entre las sustancias que pueden reducir el efecto hipoglucemiante se incluyen los corticosteroides, el danazol, el diazóxido, los diuréticos, el glucagón, la isoniazida, los estrógenos y los…»
AEMPS, section 4.5 · Open on CIMA
fibratosclass named in the label
«Entre las sustancias que pueden aumentar el efecto hipoglucemiante e incrementar la susceptibilidad a la hipoglucemia se cuentan los medicamentos antidiabéticos orales, los inhibidores de la enzima…»
AEMPS, section 4.5 · Open on CIMA
Fluoxetine
«Entre las sustancias que pueden aumentar el efecto hipoglucemiante e incrementar la susceptibilidad a la hipoglucemia se cuentan los medicamentos antidiabéticos orales, los inhibidores de la enzima…»
AEMPS, section 4.5 · Open on CIMA
inhibidores de la ECAclass named in the label
«Entre las sustancias que pueden aumentar el efecto hipoglucemiante e incrementar la susceptibilidad a la hipoglucemia se cuentan los medicamentos antidiabéticos orales, los inhibidores de la enzima…»
AEMPS, section 4.5 · Open on CIMA
Lithium
«Los betabloqueantes, la clonidina, las sales de litio o el alcohol pueden potenciar o debilitar el efecto hipoglucemiante de la insulina. La pentamidina puede provocar hipoglucemia, que algunas veces…»
AEMPS, section 4.5 · Open on CIMA
Olanzapine
«Entre las sustancias que pueden reducir el efecto hipoglucemiante se incluyen los corticosteroides, el danazol, el diazóxido, los diuréticos, el glucagón, la isoniazida, los estrógenos y los…»
AEMPS, section 4.5 · Open on CIMA
simpaticomiméticosclass named in the label
«Entre las sustancias que pueden reducir el efecto hipoglucemiante se incluyen los corticosteroides, el danazol, el diazóxido, los diuréticos, el glucagón, la isoniazida, los estrógenos y los…»
AEMPS, section 4.5 · Open on CIMA

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Frequently asked

What is Insulin glargine used for?

Insulin glargine is evaluated for the following indications with varying evidence strength: Type 1 diabetes mellitus (evidence tier A), Insulin-dependent type 2 diabetes mellitus (evidence tier A), Muscle mass gain (bodybuilding self-use) (evidence tier F). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Insulin glargine?

Common side effects of Insulin glargine (≥ 1 in 100): Hypoglycaemia: sweating, tremor, palpitations, hunger, confusion, Injection site reactions: redness, swelling, itching, Lipohypertrophy when injections stay in one spot, Weight gain early in treatment. See the Safety section for uncommon and serious reactions.

Is Insulin glargine safe during pregnancy?

Is Insulin glargine compatible with breastfeeding?

Who should not take Insulin glargine?

Insulin glargine is contraindicated in: Hypoglycaemia; Hypersensitivity to insulin or to any excipient of the product. Full list in the Safety section.

Official sources

Direct links to regulator labels. Open in a new tab.

AEMPS / CIMA

Other drugs in this group

Insulin glulisine, Insulin human isophane (NPH), Insulin lispro, Linagliptin, Semaglutide, Vildagliptin + Metformin, Glimepiride, Liraglutide