Long-acting analogue insulin Pregnancy: A large amount of data (>1000 pregnancy outcomes) indicates no specific adverse effect on pregnancy nor malformative or feto/neonatal toxicity; use may be considered during pregnancy if clinically needed. Insulin requirements may decrease during the first trimester and generally increase during the second and third; they decline rapidly immediately after delivery. Breast-feeding women may need insulin dose and diet adjustments.

Insulin glargine

Brand names: Lantus, Abasaglar, Toujeo, Semglee

A long-acting basal insulin analogue given by subcutaneous injection, typically once daily, to provide background insulin cover in type 1 and type 2 diabetes.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Individualised (no fixed dose stated) - dose and timing adjusted to the patient

Route: Subcutaneous (must NOT be given intravenously)

Frequency: Once daily, at the same time each day

Long-acting basal insulin analogue (SPC: ABASAGLAR 100 units/mL). In type 2 diabetes may be combined with orally active antidiabetic agents. Potency is stated in units exclusive to insulin glargine (not the same as IU or units of other analogues). Intravenous administration of the usual subcutaneous dose could cause severe hypoglycaemia. Do not mix or dilute with any other insulin. Rotate injection sites (abdomen, deltoid or thigh) to reduce lipodystrophy/cutaneous amyloidosis. Not the insulin of choice for diabetic ketoacidosis (use intravenous regular insulin). Switching: from twice-daily NPH insulin reduce the daily basal dose by 20-30% during the first weeks; from insulin glargine 300 units/ml reduce dose by approximately 20% (products not bioequivalent/interchangeable). Paediatric: safety and efficacy established in children aged 2 years and older (dose and timing individually adjusted); not established below 2 years. Interaction list drawn from the US product label (BASAGLAR) as the captured UK SPC sections did not include section 4.5.

Dose adjustments

Renal

In renal impairment, insulin requirements may be diminished due to reduced insulin metabolism; in the elderly, progressive deterioration of renal function may lead to a steady decrease in insulin requirements.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to insulin glargine or to any of the excipients

Side effects

Hypoglycaemia (very common) - may be severe, recurrent episodes may cause neurological damage and may be life-threatening
Lipohypertrophy, lipoatrophy or cutaneous amyloidosis at the injection site (may delay local insulin absorption)
Injection site reactions; oedema
Allergic reactions (immediate-type rare; may include generalised skin reactions, angio-oedema, bronchospasm, hypotension and shock - may be life-threatening)
Visual impairment and retinopathy (marked change in glycaemic control may cause temporary visual impairment); dysgeusia; myalgia

Interactions

Drugs that may increase the risk of hypoglycaemia (may need dose reduction and more frequent glucose monitoring): other antidiabetic agents, ACE inhibitors, angiotensin II receptor blockers, disopyramide, fibrates, fluoxetine, MAO inhibitors, pentoxifylline, pramlintide, salicylates, somatostatin analogues (e.g. octreotide), sulfonamide antibiotics
Drugs that may reduce the blood-glucose-lowering effect (may need dose increase): atypical antipsychotics (e.g. olanzapine, clozapine), corticosteroids, danazol, diuretics, oestrogens, glucagon, isoniazid, niacin, oral contraceptives, phenothiazines, progestogens, protease inhibitors, somatropin, sympathomimetics (e.g. albuterol, adrenaline, terbutaline), thyroid hormones
Alcohol, beta-blockers, clonidine and lithium salts may increase or decrease the glucose-lowering effect; pentamidine may cause hypoglycaemia sometimes followed by hyperglycaemia; beta-blockers may mask hypoglycaemia warning symptoms

Clinical monograph

How it works

It precipitates as microcrystals in the neutral pH of subcutaneous tissue, producing a slow, relatively peakless release that gives a prolonged, steady basal insulin effect.

Prescribing in practice

Hypoglycaemia is the principal risk; never administer intravenously and do not mix in a syringe with other insulins, as this alters its absorption profile.
Be aware that different glargine strengths and biosimilar brands are not interchangeable unit-for-unit, so prescribe and switch by brand to avoid dosing errors.
Insulin requirements may change with illness, weight change, renal impairment or altered physical activity, requiring dose review.

Monitoring

Monitor capillary or interstitial glucose and HbA1c, paying particular attention to fasting glucose and nocturnal hypoglycaemia when titrating the dose.

Counselling the patient

Inject once daily at the same time each day and rotate injection sites within an area.
Recognise and treat hypoglycaemia promptly, and never stop insulin during illness without advice.
Store in-use pens at room temperature and spare cartridges in the refrigerator without freezing.

Evidence & guidelines

Basal insulin analogues are established in NICE guidance for type 1 and type 2 diabetes, offering comparable glycaemic control to NPH insulin with a lower risk of nocturnal hypoglycaemia.

Reference: NICE NG17/NG28; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways