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Evidence: HighProtein, not a peptideFDA ApprovedFirst rapid analogueFDA approved 1996Now has a faster version

Insulin lispro

The first insulin analogue, made by swapping two amino acids, and the drug newer therapies are measured against

Insulin lispro was the first insulin analogue: two amino acids near the end of the B chain are reversed, which stops the molecules clumping and lets them absorb fast enough to take with a meal. An ultra-rapid version followed, and in 2023 a weekly GLP-1 drug beat it outright.

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Overview

What is it?

Human insulin clumps into hexamers in the vial and must come apart before absorption, which is why older mealtime insulin had to be injected well before eating. Reversing two amino acids on the B chain weakens that clumping. The result absorbs fast enough to inject at the meal: the Humalog label puts peak levels at 30 to 90 minutes against 50 to 120 for regular insulin, with a half-life after injection of about 1 hour against 1.5.

The long-term data are reassuring in a specific way: after up to 5.4 years of use, free insulin levels were still higher at 30 and 60 minutes than with human soluble insulin, and antibody levels were no higher than at one year. Biosimilar versions have since matched its pharmacokinetics.

An ultra-rapid version, Lyumjev, adds excipients that speed absorption further. Across its trials it matched lispro for HbA1c and lowered post-meal glucose: in children, in insulin pumps, and in mostly Chinese adults. When people exercised after a meal, the glucose drop was smaller. In closed-loop systems the gains are modest, less variability and slightly less time low rather than more time in range.

Inhaled insulin is faster still, beginning to act within 15 minutes and wearing off sooner than lispro, which is why the two are not dosed unit for unit.

The most striking recent result is not about insulin at all. In SURPASS-6, weekly tirzepatide added to basal insulin beat mealtime lispro, with hypoglycaemia at 0.4 against 4.4 events per patient-year.

The Humalog label allows injection within 15 minutes before a meal or right after it, use in insulin pumps for the U-100 strength, and intravenous infusion only after dilution under supervision; the concentrated U-200 pen is for injection only.

≤15 min
Before a meal, or right after
Humalog label 2.2
30-90 min
Peak level vs 50-120 for regular insulin
Label 12.3
0.4 vs 4.4
Hypoglycaemia per year, tirzepatide vs lispro
SURPASS-6
Science

Mechanism of Action

Insulin lispro is human insulin with two B-chain amino acids swapped, which weakens hexamer formation so it absorbs fast enough to take with a meal.

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Swapped B28-B29

Reversing proline and lysine at B28 and B29 weakens self-association into hexamers.

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Fast absorption

Peak levels 30 to 90 minutes after injection; half-life about 1 hour subcutaneously (label 12.3).

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Insulin receptor

Once absorbed it acts like human insulin, lowering post-meal glucose.

Evidence

Published Research

These are the trials in people, read from their PubMed abstracts: the long-term data, the faster version, a biosimilar and the comparison it lost.

Human2023

Beaten by a weekly GLP-1 drug

In SURPASS-6, weekly tirzepatide added to basal insulin was compared with mealtime insulin lispro in inadequately controlled type 2 diabetes. Hypoglycaemia below 54 mg/dL or severe was 0.4 events per patient-year with tirzepatide against 4.4 with lispro.

PMID: 37786396
Human2022

The ultra-rapid version against the original

Ultra-rapid lispro showed accelerated absorption and greater reduction in post-meal glucose than Humalog at different meal-to-dose timings, sustained over two weeks of outpatient dosing in type 2 diabetes, and was well tolerated.

PMID: 34605142
Human1999

Still working after five years

In type 1 diabetes, free insulin levels were significantly higher at 30 and 60 minutes with lispro than with human soluble insulin, and antibody levels after up to 5.4 years were not elevated beyond their one-year values.

PMID: 10342337
Human2020

Measured head to head

Ultra-rapid lispro appeared in serum 5 minutes sooner, with 6.4-fold greater exposure in the first 15 minutes, and its action began 13 minutes faster than Humalog, with similar overall exposure.

PMID: 32468448
Human2022

A biosimilar matched it

A biosimilar insulin lispro showed similar pharmacokinetics and pharmacodynamics to the originator in Japanese participants.

PMID: 35166054
Human2024

Ultra-rapid lispro in mostly Chinese patients

In type 1 diabetes, ultra-rapid lispro matched lispro for HbA1c at 26 weeks and lowered 1- and 2-hour post-meal glucose rises by 1.0 and 1.4 mmol/L.

PMID: 37871985
Human2025

Closed loop with a missed bolus

In 17 people on fully closed-loop delivery simulating a missed meal bolus, ultra-rapid lispro gave numerically more time in range than standard lispro (49.3% against 39.9%), a difference that was not significant.

PMID: 40815068
Human2023

PRONTO-Peds: children and teenagers

In children and adolescents with type 1 diabetes, ultra-rapid lispro at mealtime or after the meal was non-inferior to lispro for HbA1c, and mealtime dosing lowered 1-hour post-meal glucose, with similar hypoglycaemia.

PMID: 36054737
Human2021

PRONTO-Pump-2: in insulin pumps

In pump users with type 1 diabetes, ultra-rapid lispro matched lispro for HbA1c and lowered post-meal glucose by 1.3 to 1.5 mmol/L at 1 and 2 hours, with less time in hypoglycaemia.

PMID: 33687783
Human2026

Exercise after a meal

In 25 adults with type 1 diabetes exercising after a meal bolus, ultra-rapid lispro produced a smaller glucose drop than lispro at both full and half bolus doses, with numerically less hypoglycaemia.

PMID: 41885780
Human2022

Against inhaled insulin

In type 1 diabetes, inhaled Technosphere insulin began acting in 7 to 15 minutes against 21 to 38 for subcutaneous lispro and wore off sooner (2 to 6 against 5 to 10 hours), so the two need different doses.

PMID: 34773608
Review2025

Faster insulins in closed-loop systems

Pooling closed-loop studies, ultra-rapid lispro or faster aspart did not significantly raise time in range over standard insulins, but reduced glucose variability and time below 70 mg/dL.

PMID: 40547532
Dosing

Dosing Data

Humalog is injected within 15 minutes before or right after a meal, used in pumps (U-100), or infused intravenously after dilution under supervision; doses are individualised.

Insulin: hypoglycaemia is the main risk; the U-200 pen is never used in pumps or intravenously.
ProtocolDoseFrequencyDurationRoute
Label: mealtime subcutaneous injection (U-100 or U-200) Approved labelHumalog (insulin lispro) injection US prescribing information (Eli Lilly; DailyMed set 51d3dc11, effective January 24, 2024)IndividualisedWithin 15 minutes before or right after a mealOngoing, usually with a basal insulinSubcutaneous
Label: insulin pump (U-100 only) Approved labelHumalog (insulin lispro) injection US prescribing information (Eli Lilly; DailyMed set 51d3dc11, effective January 24, 2024)IndividualisedContinuous subcutaneous infusionPer pump instructionsSubcutaneous infusion
Label: intravenous (U-100 only) Approved labelHumalog (insulin lispro) injection US prescribing information (Eli Lilly; DailyMed set 51d3dc11, effective January 24, 2024)Individualised, after dilutionContinuousUnder medical supervisionIntravenous

Educational information, not medical advice. Each dose above is tagged with its source: an approved label, a published human study, animal data, or amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.

Dosed in units
Lispro is 100 or 200 units/mL; pens dial in units, and the U-200 strength is not used in pumps or intravenously.
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Safety

Side Effects & Contraindications

Reported Side Effects

The risks of any mealtime insulin.

● Hypoglycaemia, quantified against an alternative in SURPASS-6 at 4.4 events per patient-year
● Injection-site reactions and lipodystrophy with repeated injection at one site
● Antibody formation was measured and did not rise beyond one-year levels over 5.4 years

Contraindications & Cautions

Standard for mealtime insulin.

● During an episode of low blood sugar
● Hypersensitivity to insulin lispro or its excipients
● Dose timing is tied to eating; the ultra-rapid version and the original are not interchangeable without adjustment
Questions

Frequently Asked Questions

?What makes lispro fast?

Two amino acids near the end of the B chain are reversed, which weakens the clumping that slows ordinary human insulin, so it absorbs as single molecules.

?What is ultra-rapid lispro?

Lyumjev, the same insulin with added excipients that speed absorption further; in direct comparison it cut post-meal glucose more than the original.

?Is it still first choice at mealtimes?

Not unchallenged. In SURPASS-6 weekly tirzepatide added to basal insulin beat it, with far less hypoglycaemia: 0.4 against 4.4 events per patient-year.

?Do antibodies build up over years?

In long-term follow-up, antibody levels after up to 5.4 years were not elevated beyond their one-year values.

Bibliography

References

  1. [pubmed] Rosenstock J, et al. "Tirzepatide vs Insulin Lispro Added to Basal Insulin in Type 2 Diabetes: The SURPASS-6 Randomized Clinical Trial." JAMA, 2023;330(17):1631-1640. PMID: 37786396.
  2. [pubmed] Leohr J, et al. "Ultra-rapid lispro shows faster pharmacokinetics and reduces postprandial glucose excursions versus Humalog® in patients with type 2 diabetes mellitus in a randomized, controlled crossover meal test early phase study." Diabetes Obes Metab, 2022;24(2):187-195. PMID: 34605142.
  3. [pubmed] Garg SK, et al. "Long-term efficacy of humalog in subjects with Type 1 diabetes mellitus." Diabet Med, 1999;16(5):384-7. PMID: 10342337.
  4. [pubmed] Leohr J, et al. "Pharmacokinetics and Glucodynamics of Ultra Rapid Lispro (URLi) versus Humalog(®) (Lispro) in Patients with Type 2 Diabetes Mellitus: A Phase I Randomised, Crossover Study." Clin Pharmacokinet, 2020;59(12):1601-1610. PMID: 32468448.
  5. [pubmed] Shiramoto M, et al. "Similar Pharmacokinetics and Pharmacodynamics of Biosimilar SAR342434 Insulin Lispro and Japan-Approved Humalog Insulin Lispro in Healthy Japanese Subjects." Clin Pharmacol Drug Dev, 2022;11(6):754-760. PMID: 35166054.
  6. [pubmed] Howey DC, et al. "[Lys(B28), Pro(B29)]-human insulin. A rapidly absorbed analogue of human insulin." Diabetes, 1994;43(3):396-402. PMID: 8314011.
  7. [fda-pi] FDA. Humalog (insulin lispro) prescribing information. Eli Lilly, updated 2024.
  8. [fda-pi] FDA. Lyumjev (insulin lispro-aabc) prescribing information. Eli Lilly, 2020.
  9. [clinical-trial] Ma J, et al. "Ultra-rapid lispro improved postprandial glucose control compared to insulin lispro in predominantly Chinese patients with type 1 diabetes: A prospective, randomized, double-blind phase 3 study." Diabetes Obes Metab, 2024;26(1):311-318. PMID: 37871985.
  10. [clinical-trial] Thabit H, et al. "Fully closed-loop control with ultra-rapid versus standard insulin lispro: A randomised crossover study simulating missed meal boluses." Diabet Med, 2025;42(10):e70122. PMID: 40815068.
  11. [clinical-trial] Wadwa RP, et al. "Efficacy and safety of ultra-rapid lispro versus lispro in children and adolescents with type 1 diabetes: The PRONTO-Peds trial." Diabetes Obes Metab, 2023;25(1):89-97. PMID: 36054737.
  12. [clinical-trial] Warren M, et al. "Improved postprandial glucose control with ultra rapid lispro versus lispro with continuous subcutaneous insulin infusion in type 1 diabetes: PRONTO-Pump-2." Diabetes Obes Metab, 2021;23(7):1552-1561. PMID: 33687783.
  13. [clinical-trial] Leohr JK, et al. "Ultra-Rapid Lispro Has an Improved Pharmacokinetic Profile for Exercise Compared With Lispro, Resulting in Less Exercise-Associated Hypoglycemia in Adults With Type 1 Diabetes on Open-Loop Continuous Subcutaneous Insulin Infusion." Diabetes Care, 2026;49(7):1185-1193. PMID: 41885780.
  14. [pubmed] Rakab MS, et al. "Ultra-rapid lispro or fast-acting aspart compared to standard insulin lispro and aspart using closed-loop insulin therapy: a systematic review and meta-analysis of randomized control trials." Front Endocrinol (Lausanne), 2025;16:1600157. PMID: 40547532.
  15. [pubmed] Grant M, et al. "Comparison of Pharmacokinetics and Pharmacodynamics of Inhaled Technosphere Insulin and Subcutaneous Insulin Lispro in the Treatment of Type 1 Diabetes Mellitus." Clin Pharmacokinet, 2022;61(3):413-422. PMID: 34773608.
  16. [fda-pi] Humalog (insulin lispro) injection US prescribing information (Eli Lilly; DailyMed set 51d3dc11, effective January 24, 2024), sections 2.2 and 12.3; read through openFDA October 6, 2026.

Sources & Citations

Studies were read from their PubMed abstracts; the Humalog label from DailyMed (set 51d3dc11, effective January 24, 2024) through openFDA, read October 6, 2026.

Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.

Last reviewed: 2026-10-01