AT278 (U500 ultra-rapid insulin aspart)
Arecor Therapeutics
An investigational ultra-concentrated (500 U/mL), ultra-rapid mealtime insulin aspart from Arecor. In a Phase 1 type 1 diabetes clamp study it was absorbed faster than standard aspart despite being five times more concentrated, pointing to lower injection volumes for people with high insulin needs.
The scorecard
Mealtime convention (faster onset is better): in T1D, onset of glucose-lowering action was 10 min earlier than standard aspart and serum appearance 6 min earlier; faster than today's analogs but no head-to-head vs Fiasp.[1]
Mealtime convention (faster/earlier exposure is better): 4.0-fold higher insulin exposure in the first 30 min and 8.9-fold higher early glucose-lowering effect vs aspart, so action is front-loaded — though still far from the sub-20-min ideal.[1]
Mealtime convention (shorter tail is better): front-loaded exposure implies a relatively shorter tail, but the clamp study did not report a clear duration advantage, so this is scored conservatively.[1]
Only single-dose Phase 1 clamp data exist in a small all-male T1D cohort; day-to-day and real-world absorption variability is unproven, especially at 500 U/mL.[1]
A faster, shorter-acting bolus could in principle reduce residual insulin during activity, but no exercise or hypoglycemia-flexibility data are available; scored neutral.[1]
Access convention (cheaper/more available is better): not approved anywhere, no price, no partner committed to T1D development as of 2026 — effectively inaccessible.[2]
Insulins are scored relative to their role peers (see tags: rapid, ultra-rapid, basal, inhaled). A basal insulin's onset score compares it to other basals, not to mealtime insulins.
The full picture
AT278 is an investigational mealtime (bolus) insulin from Arecor, built on its Arestat formulation technology. It is unusual in two ways at once: it is ultra-concentrated at 500 U/mL — five times the strength of standard insulin aspart — yet engineered to be absorbed faster, not slower. Normally, concentrating insulin slows absorption, so combining high strength with rapid onset is the technical achievement.
The key evidence comes from a Phase 1, double-blind, randomized crossover clamp study in 38 men with type 1 diabetes, comparing a single dose of AT278 against standard insulin aspart. AT278 reached the bloodstream about 6 minutes earlier and began lowering glucose about 10 minutes earlier. Early exposure was 4.0-fold higher in the first 30 minutes, and the early glucose-lowering effect was 8.9-fold higher in the first 30 minutes — a strongly front-loaded profile that more closely mimics a meal-time insulin burst.
The practical promise is twofold: faster post-meal coverage, and a much smaller injection volume for people with high insulin requirements, including pump users. The limitations are real — only single-dose Phase 1 data exist, in a small all-male cohort, with no Phase 2/3 program or regulatory submission for type 1 diabetes reported as of 2026. Arecor has been seeking a development partner to take it forward.
Coming soon
ETA · Phase 1 complete in type 1 diabetes (2023); no Phase 2/3 in T1D reported and no approval as of 2026. A development/licensing partner is being sought to advance it.
- →Needs a Phase 2/3 program and a commercial partner before any approval; none announced for type 1 diabetes as of 2026
- →If developed, the 500 U/mL strength would cut injection volume ~5-fold for people on large doses or in pumps
Sources
- [1]Svehlikova E, et al. Pharmacokinetics and Pharmacodynamics of a Novel U500 Insulin Aspart Formulation: A Randomized, Double-Blind, Crossover Study in People With Type 1 Diabetes. Diabetes Care 2023;46(4):757-764 · peer-reviewed · 2023-04-01
- [2]Arecor Therapeutics — Diabetes portfolio (AT278 ultra-concentrated ultra-rapid insulin) · manufacturer
- [3]Arecor announces publication of Phase 1 data for AT278 in Diabetes Care · news · 2023-01-30