Short answer: Both are insulin aspart, a mealtime insulin for adults and children with diabetes.12 Fiasp adds niacinamide and is injected at the start of a meal or within 20 minutes after starting. NovoLog is injected 5 to 10 minutes before a meal. In the Fiasp label's trials against NovoLog, HbA1c results met the set non-inferiority margin. Neither has a boxed warning.
| Fiasp | NovoLog | |
|---|---|---|
| What is in it | Insulin aspart 100 units/mL; inactive ingredients include niacinamide and arginine1 | Insulin aspart 100 units/mL2 |
| When injected | At the start of a meal or within 20 minutes after starting a meal1 | Within 5 to 10 minutes before a meal2 |
| How fast (label studies) | Insulin appeared in the blood about 2.5 minutes after a dose; peak level at about 63 minutes1 | Median time to peak level 40 to 50 minutes2 |
| Type 1 adults, 26 weeks (Study A) | HbA1c change −0.32% mealtime, −0.13% after the meal1 | −0.17% mealtime1 |
| Type 2 adults, 26 weeks (Study B) | HbA1c change −1.38%1 | −1.36%1 |
| Insulin pump | Change the reservoir at least every 6 days; a PumpCart cartridge every 4 days1 | Change the reservoir at least every 7 days2 |
| Mixing in a syringe | Not mixed with any other insulin1 | May be mixed with NPH insulin only2 |
| Missed dose | Check blood sugar to decide if a dose is needed; resume at the next meal1 | No instruction in the label2 |
| Boxed warning | None1 | None2 |
Four Fiasp trials used NovoLog as the comparator, each with a non-inferiority margin of 0.4% HbA1c. In adults with type 1 diabetes over 26 weeks, HbA1c fell 0.32% on mealtime Fiasp, 0.13% on Fiasp after the meal and 0.17% on mealtime NovoLog. In type 2 diabetes it fell 1.38% vs 1.36%. In children with type 1 diabetes, HbA1c rose 0.06% on mealtime Fiasp, 0.35% on Fiasp after the meal and 0.22% on NovoLog. On an insulin pump over 16 weeks, it fell 0.04% on Fiasp vs 0.14% on NovoLog.1
The same label reports more confirmed lows on Fiasp than NovoLog in two settings: within the first hour after a meal in adults on a pump, and in children, more so at night.1
The Fiasp label says a change from another mealtime insulin can start unit for unit, with closer glucose checks; in the type 1 adult trial, people were switched that way. The NovoLog label says a different dose may be needed when switching from another insulin.12 Both labels share the usual insulin warnings: low blood sugar, never sharing pens, medication mix-ups, low potassium and pump failure.
Which, if either, fits is for your prescriber. More detail: Fiasp side effects, the Fiasp dosing schedule, the Fiasp and NovoLog missed-dose pages, how to store Fiasp, how to store NovoLog and Humalog vs NovoLog: what is different between the two mealtime insulins?.