insulin lispro
Humalog (insulin lispro) is a rapid-acting insulin from Eli Lilly. Two swapped amino acids make it absorb quickly after injection, so it covers the rise in blood sugar that follows a meal, and it is used in type 1 and type 2 diabetes.
This page is based on FDA prescribing information and the EMA medicine record for insulin lispro, cross-checked with the National Cancer Institute drug dictionary; 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. After a meal, blood sugar rises fast and the body needs many managers right away. Insulin lispro is a fast-acting stand-in: injected just before eating, it dissolves into active molecules within minutes, opening the doors quickly so glucose from the meal can move into cells.
In simple terms
Insulin is the hormone that lets cells absorb glucose from the blood. After a meal, blood sugar rises quickly, and the body needs a fast burst of insulin. Insulin lispro is a modified human insulin designed to act rapidly. Injected under the skin just before a meal, it is absorbed quickly and starts working within minutes, covering the rise in blood sugar that follows eating. Its effects peak in about one to two hours and fade over three to five hours.
In depth
Insulin lispro differs from human insulin by reversal of the amino acids proline at B28 and lysine at B29, which reduces self-association of hexamers and accelerates absorption from the subcutaneous depot. The resulting rapid rise in insulin levels mirrors the prandial insulin response of a person without diabetes. Lispro insulin is equipotent to human insulin on a molar basis but has a faster onset and shorter duration. It is used as mealtime insulin and may be formulated as a mixture with insulin lispro protamine for combined prandial and basal coverage.
See it in motion
A schematic animation of the mechanism — simplified for clarity, not drawn to scale.
How the B28-B29 reversal makes insulin lispro act within minutes
- Insulin lispro differs from human insulin by reversal of the amino acids proline at B28 and lysine at B29, which reduces self-association of hexamers and accelerates absorption from the subcutaneous depot.
- Its effects peak in about one to two hours and fade over three to five hours.
- Lispro insulin is equipotent to human insulin on a molar basis but has a faster onset and shorter duration.
- It is used as mealtime insulin and may be formulated as a mixture with insulin lispro protamine for combined prandial and basal coverage.
Target: Insulin receptor
The receptor through which insulin tells muscle, fat, and liver cells to take up glucose; a rapid-acting insulin covers the spike in blood sugar that follows meals.
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 with diabetes mellitus
Approved uses in European Union
EMA- For the treatment of adults and children with diabetes mellitus who require insulin for the maintenance of normal glucose homeostasis; also indicated for the initial stabilisation of diabetes mellitus
Official sources
The statements on this page trace back to these records.
- U.S. Food and Drug Administration: Humalog (insulin lispro) prescribing information
U.S. Food and Drug Administration
- Humalog (insulin lispro) — Summary of product characteristics and package leaflet, English version
European Medicines Agency
- National Cancer Institute: insulin lispro
National Cancer Institute
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.