Insulin lispro (Humalog) and insulin aspart (NovoLog/Novorapid) are two rapid-acting insulin analogues used to manage postprandial glucose excursions. Both provide faster onset and shorter duration than regular human insulin, but differ in their pharmacokinetic profiles, formulation options, and clinical applications.
| Property | Insulin Lispro | Insulin Aspart |
|---|
| Brand names | Humalog, Admelog | NovoLog, Novorapid |
| Manufacturer | Eli Lilly | Novo Nordisk |
| Sequence modification | ProB28→Lys, LysB29→Pro | ProB28→Asp |
| Molecular weight | 5,808 Da | 5,826 Da |
| Structural effect | Disrupted dimer formation | Disrupted dimer formation |
| Concentration | U-100, U-200 | U-100, U-200 |
Both analogues disrupt the hexameric self-association of insulin through B28/B29 modifications, resulting in faster absorption from subcutaneous tissue.
| Parameter | Insulin Lispro (U-100) | Insulin Aspart (U-100) |
|---|
| Onset | 5–15 minutes | 5–15 minutes |
| Peak | 30–90 minutes | 30–90 minutes |
| Duration | 3–5 hours | 3–5 hours |
| Time to 50% AUC | ~1.5 hours | ~1.5 hours |
| Bioavailability | 55–75% | 55–75% |
| Metric | Lispro | Aspart | Clinical Significance |
|---|
| Maximum plasma concentration (Tmax) | ~60 min | ~60 min | Similar postprandial coverage |
| Early glucose control (0–60 min) | Slightly faster | Slightly slower | Marginal difference |
| Duration of action | 3–5 hours | 3–5 hours | Similar basal coverage |
In clinical practice, the pharmacokinetic differences between lispro and aspart are generally considered negligible for most patients.
| Product | Formulation | Duration | Notes |
|---|
| Humalog (U-100) | Standard | 3–5 hours | First-line rapid-acting |
| Humalog (U-200) | Concentrated | 3–5 hours | High-dose patients |
| Humalog Mix 50/50 | 50% lispro protamine / 50% lispro | 12–16 hours | Twice-daily |
| Humalog Mix 75/25 | 75% lispro protamine / 25% lispro | 12–16 hours | Twice-daily |
| Admelog | Biosimilar lispro | 3–5 hours | Lower cost |
| Lyumjev | Ultra-rapid lispro | 2–4 hours | Faster early action |
| KwikPen | Pre-filled pen | 3–5 hours | Convenience |
| Product | Formulation | Duration | Notes |
|---|
| NovoLog (U-100) | Standard | 3–5 hours | First-line rapid-acting |
| NovoLog (U-200) | Concentrated | 3–5 hours | High-dose patients |
| NovoMix 30 | 30% aspart protamine / 70% aspart | 12–16 hours | Twice-daily |
| Fiasp | Ultra-rapid aspart | 2–4 hours | Faster early action |
| NovoLog FlexPen | Pre-filled pen | 3–5 hours | Convenience |
| NovoRapid PumpCart | Pump cartridge | 3–5 hours | Insulin pump use |
| Parameter | Lyumjev | Humalog |
|---|
| Onset | 5–10 minutes | 15–30 minutes |
| Peak | 45–75 minutes | 60–90 minutes |
| Duration | 2–4 hours | 3–5 hours |
| Additives | Treprostinil, citrate | None |
| Parameter | Fiasp | NovoLog |
|---|
| Onset | 5–10 minutes | 15–30 minutes |
| Peak | 45–75 minutes | 60–90 minutes |
| Duration | 2–4 hours | 3–5 hours |
| Additives | Niacinamide, L-arginine | None |
- 1 unit of insulin lispro ≈ 1 unit of insulin aspart
- No dose conversion required when switching between analogues
- Both are dosed based on carbohydrate ratio and correction factor
| Scenario | Lispro | Aspart |
|---|
| Pre-meal dosing (0–15 min before) | Standard | Standard |
| Post-meal dosing (0–20 min after) | Standard | Standard |
| Insulin pump use | Standard | Standard |
| Closed-loop systems | Compatible | Compatible |
| Time Period | Lispro | Aspart |
|---|
| Early postprandial (0–2 hours) | Low | Low |
| Late postprandial (2–5 hours) | Moderate | Moderate |
| Nocturnal (when dosed at dinner) | Low | Low |
Both analogues have similar hypoglycemia profiles when dosed appropriately.
- Direct 1:1 conversion is appropriate for most patients
- Monitor glucose patterns for 3–5 days after switching
- Adjust basal insulin if needed
- Recalculate insulin-to-carb ratios if switching ultra-rapid formulations
| Factor | Recommendation |
|---|
| Pump users | Consider pump cartridge compatibility |
| Cost | Compare biosimilar availability |
| Ultra-rapid needs | Lyumjev or Fiasp may be preferred |
| Mix formulations | Different mix ratios may require dose adjustment |
| Product | Approximate Cost (30-day supply) | Biosimilar Available? |
|---|
| Humalog U-100 | $275–350 | Yes (Admelog) |
| NovoLog U-100 | $275–350 | Yes (Various) |
| Lyumjev | $300–400 | No |
| Fiasp | $300–400 | No |
- Howey DC, et al. “Lyspro, a fast-acting insulin analog.” Diabetes Care 1994;17:708-713.
- Home PD, et al. “Insulin aspart: a fast-acting insulin analogue.” Diabetes Care 1999;22:1405-1412.
- Russell-Jones D, et al. “Fiasp (faster-acting insulin aspart) vs NovoRapid in type 1 diabetes (ONSET 1).” Diabetes Obes Metab 2019;21:1615-1624.
