Insulin lispro !

A rapid-acting insulin analogue for meals: it is absorbed faster and acts for a shorter time than regular human insulin.

Updated 2026-11-01

Class: Insulins
Receptor: Insulin receptor
ATC code: A10AB04
WHO Model List of Essential Medicines

Insulin receptorInsulin lispro

The figure shows human insulin bound to site 1 of an insulin receptor fragment. Lispro differs only at B28–B29, which changes how it self-associates, and binds the same site.

Target in 3D: Insulin receptor. PDB structure 4OGA (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

In lispro the proline at B28 and lysine at B29 are swapped. This weakens the contacts that hold insulin together as hexamers, so after injection it splits almost at once into monomers that are absorbed quickly. At the receptor it acts like human insulin and is equipotent unit for unit; only the timing changes.

Swapped B28–B29 residues weaken hexamer formation
Monomers are absorbed quickly from under the skin
Activates the insulin receptor like human insulin
Covers the glucose rise of a meal, then wears off sooner

Pharmacokinetics

Absorption: Subcutaneous, faster than regular human insulin; it can also be given intravenously under medical supervision.
Half-life: After a subcutaneous injection, about 1 hour (versus about 1.5 hours for regular insulin).
Onset and duration: Rapid onset and shorter duration than regular insulin; it is given within 15 minutes before or right after a meal.

Indications

Mealtime and correction insulin in type 1 diabetes, by injection or insulin pump Type 1 diabetes mellitus →
Mealtime insulin in type 2 diabetes Type 2 diabetes mellitus →

Adverse effects

Common

Hypoglycemia
Weight gain
Injection-site reactions and lipodystrophy
Low potassium

Contraindications

During an episode of hypoglycemia
Hypersensitivity to insulin lispro or an excipient

Key interactions

Beta-blockers, clonidine: Can blunt the warning signs of hypoglycemia.
Alcohol, lithium, pentamidine: Can increase or decrease the glucose-lowering effect.
Corticosteroids, diuretics, atypical antipsychotics, niacin, oral contraceptives: Reduce the glucose-lowering effect.
Thiazolidinediones (pioglitazone): Fluid retention and possible heart failure.

What is monitored

Blood glucose before and after meals
HbA1c
Potassium and glucose during intravenous use
Injection or pump sites

Administration and safety

Subcutaneous injection close to the meal, or continuous subcutaneous infusion by pump.
Intravenous use only under medical supervision, with close monitoring of glucose and potassium.
In a pump it is not diluted or mixed with any other insulin.
Look-alike risk with other rapid analogues, mixtures and concentrated forms: the label and concentration are checked.

Nursing care

Before: check glucose and confirm the meal tray is present or the patient will eat.
After: watch for hypoglycemia in the first hours after the dose.
If the patient vomits or cannot eat, the dose is reviewed with the team.
Teach pump users the signs of pump failure (rising glucose, ketones).

Pregnancy and breastfeeding

Rapid analogues such as lispro are widely used in pregnancy; insulin needs change by trimester and glucose is checked often.

Test yourself

Think of the answer, then tap the question to see it.

Why does lispro act faster than regular insulin if both bind the same receptor?

Swapping proline B28 and lysine B29 weakens self-association, so lispro dissociates into absorbable monomers almost at once.

When is lispro given relative to a meal?

Within about 15 minutes before or right after eating, unlike regular insulin, which is given earlier.

A patient on a lispro pump has a blocked catheter. Why can ketoacidosis develop quickly?

A pump uses only rapid insulin; with no long-acting depot, insulin levels fall within hours when delivery stops.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: Insulin Lispro Injection: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); DailyMed - INSULIN LISPRO injection, solution (DailyMed (U.S. National Library of Medicine), 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 51 (McGraw Hill, 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.