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When does insulin lispro peak / how long does it last?

Medically reviewed by Carmen Pope, BPharm. Last updated on June 16, 2022.

Official answer

  • Lispro peaks 30 to 90 minutes after administration
  • Lispro lasts for less than five hours (usually two to four hours).
  • Lispro is an analog insulin that is made by genetically modifying the structure of human insulin to give it a faster onset of effect and a shorter duration of action.
  • This makes it more convenient for people with diabetes to administer as it only needs to be given within 15 minutes of a meal.
  • Lispro is also less likely to cause hypoglycemia than regular insulin.

Insulin Lispro is an analog insulin. It is made by genetically modifying the structure of human insulin to allow it to be absorbed more quickly and last for a shorter length of time than regular insulin. Lispro:

  • Starts working within 0 to 15 minutes after administration
  • Peaks in 30 to 90 minutes
  • Keeps working for less than five hours (usually two to four hours).

This means it can be administered 15 minutes before or with a meal. This has safety benefits over regular insulin that needs to be administered 30 minutes before food, especially if a meal is delayed or forgotten because hypoglycemia may result.

Lispro also has a shorter duration of effect than regular insulin. This means lispro better mimics how insulin is naturally released in people without diabetes and reduces the risk of side effects such as low blood sugar levels (hypoglycemia) following a meal.

How is Lispro made?

Insulin lispro is an analog insulin. An analog insulin is a genetically modified insulin. Human insulin is made up of a linked A and B polypeptide chains and insulin lispro is made by switching the sequence of two beta-chain amino acids: the proline at B-28 is switched with the lysine at B-29.

This results in more rapid dissolution of the insulin to a dimer and then to a monomer which means it is absorbed more rapidly after subcutaneous injection and lasts for less than five hours.

Although one unit of insulin lispro has the same glucose-lowering effect as one unit of regular insulin, it has:

  • Faster subcutaneous absorption
  • An earlier and greater insulin peak
  • More rapid post-peak decreases.

A longer-acting form of insulin lispro is also available called insulin lispro protamine suspension. Humalog 75:25 contains insulin lispro protamine suspension as the intermediate-acting insulin and insulin lispro as the short-acting insulin.


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