insulin glargine
Brand: Lantus, Basaglar, Toujeo
ISMP High Alert Prototype Drug
Drug Class: insulin
Drug Family: insulin
Subclass: long-acting insulin analogue
Organ Systems: endocrine
Mechanism of Action
Recombinant human insulin analogue with amino acid substitutions creating a microprecipitate at physiologic pH after SC injection; slowly dissolves and is absorbed, providing a relatively flat (peakless) 24-hour basal insulin profile without pronounced peaks.
insulin receptor (IR)IGF-1 receptor
Indications
- type 1 diabetes mellitus (basal insulin)
- type 2 diabetes mellitus (basal insulin)
Contraindications
- hypoglycemic episodes (withhold and reassess)
- hypersensitivity to insulin glargine
Adverse Effects
Common
- hypoglycemia
- injection site reactions (lipohypertrophy, lipoatrophy)
- weight gain
Serious
- severe hypoglycemia (altered consciousness, seizure, coma)
- hypokalemia
- anaphylaxis (rare)
- local allergic reactions
Pharmacokinetics (ADME)
| Absorption | SC only; forms subcutaneous depot; onset 2–4 hours, peak minimal, duration 20–24+ hours |
| Distribution | Protein binding minimal in circulation |
| Metabolism | Cleaved to active metabolites at B-chain carboxy terminus in peripheral tissues |
| Excretion | Renal |
| Half-life | ~12 hours (SC absorption-limited) |
| Onset | 2–4 hours |
| Peak | No pronounced peak |
| Duration | ~24 hours (Lantus/Basaglar); ~36 hours (Toujeo 300 units/mL) |
| Protein Binding | minimal |
| Vd | N/A (SC depot) |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| beta-blockers | mask tachycardia (not sweating) as hypoglycemia warning sign; non-selective beta-blockers may also impair glycogenolysis | moderate |
| corticosteroids / thiazides / atypical antipsychotics | increase blood glucose; may require insulin dose increase | moderate |
| ACE inhibitors / salicylates | may increase insulin sensitivity; hypoglycemia risk | minor |
Nursing Considerations
- Administer at the same time each day — always SC, never IV; do NOT mix with other insulins or inject in the same syringe as other insulin preparations
- Rotate injection sites within the same region to prevent lipohypertrophy — injecting into hypertrophied tissue causes erratic absorption and poor glycemic control
- Monitor fasting blood glucose and bedtime glucose; target fasting glucose typically 80–130 mg/dL per ADA guidelines; adjust dose by 2 units every 3 days based on fasting glucose pattern
- Educate patient about signs/symptoms of hypoglycemia and 15-15 rule: if glucose <70 mg/dL, treat with 15g fast-acting carbohydrate and recheck in 15 minutes
Clinical Pearls
- Glargine cannot be mixed with other insulins — its unique pH-dependent precipitation mechanism is disrupted by mixing, resulting in altered kinetics and loss of the peakless profile
- Toujeo (300 units/mL) has an even longer duration (≥36 hours) than Lantus (100 units/mL) due to a more concentrated and slowly-dissolving depot — useful for patients needing once-daily dosing with extended coverage
Safety Profile
Pregnancy use-with-caution
Lactation safe
Renal Adjustment Required
Hepatic Adjustment Required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.