There are seven main categories of insulin — rapid-acting, ultra-rapid, short-acting, intermediate, long-acting, ultra-long-acting, and premixed — each differing in onset, peak, and duration. The right choice depends on diabetes type, meal pattern, hypoglycemia risk, cost, and personal preference. Most people with type 1 diabetes use a rapid analog at meals plus a long-acting analog once or twice daily (basal-bolus), while most people with type 2 diabetes start with a single long-acting injection added to oral therapy. This guide compares every commonly used insulin by pharmacokinetics, brand, cost, and clinical fit.
The Master Comparison Table
| Category | Generic Name | Brand(s) | Onset | Peak | Duration |
|---|---|---|---|---|---|
| Ultra-rapid | insulin aspart faster | Fiasp | 2–5 min | 1–2 h | 3–5 h |
| Ultra-rapid | insulin lispro-aabc | Lyumjev | 2–5 min | 1–2 h | 3–5 h |
| Inhaled | insulin human | Afrezza | 1–3 min | ~12 min | 1.5–3 h |
| Rapid | insulin lispro | Humalog, Admelog | 10–15 min | 1–2 h | 3–5 h |
| Rapid | insulin aspart | Novolog, Fiasp | 10–15 min | 1–2 h | 3–5 h |
| Rapid | insulin glulisine | Apidra | 10–15 min | 1–2 h | 3–5 h |
| Short (regular) | human regular | Humulin R, Novolin R | 30–60 min | 2–4 h | 5–8 h |
| Intermediate | NPH | Humulin N, Novolin N | 1–2 h | 4–10 h | 12–18 h |
| Long-acting | insulin detemir | Levemir | 1–2 h | ~6–8 h (mild) | 18–24 h |
| Long-acting | insulin glargine U-100 | Lantus, Basaglar, Semglee, Rezvoglar | 1–2 h | flat | 20–24 h |
| Long-acting | insulin glargine U-300 | Toujeo | 2–6 h | flat | 30–36 h |
| Ultra-long | insulin degludec | Tresiba | ~1 h | flat | >42 h |
| Premix | NPH + Regular 70/30 | Humulin 70/30, Novolin 70/30 | 30–60 min | dual | 10–18 h |
| Premix | lispro mix 75/25 | Humalog Mix 75/25 | 10–20 min | dual | 10–22 h |
| Premix | aspart mix 70/30 | Novolog Mix 70/30 | 10–20 min | dual | up to 24 h |
| Premix (basal + bolus) | degludec + aspart 70/30 | Ryzodeg 70/30 | 10–15 min | aspart peak | >24 h |
Rapid-Acting Insulin Analogs
Rapid-acting analogs are engineered versions of human insulin with amino-acid swaps that prevent self-aggregation in solution, so they absorb quickly and act fast. They are the workhorse mealtime insulins of modern diabetes care.
- Insulin lispro — Humalog (Eli Lilly), Admelog (Sanofi biosimilar). Lysine-proline swap at B28-B29.
- Insulin aspart — Novolog (Novo Nordisk). Aspartic acid replaces proline at B28.
- Insulin glulisine — Apidra (Sanofi). Lysine-glutamic acid substitutions; no zinc in formulation.
Dose right before eating (or up to 15 minutes before). Duration of 3 to 5 hours matches one meal — covers it without much overlap into the next.
Ultra-Rapid Analogs
- Fiasp — insulin aspart with niacinamide and L-arginine to accelerate absorption. Onset 2 to 5 minutes; dose at meal start or up to 20 minutes after.
- Lyumjev — insulin lispro with treprostinil and citrate; similar fast kinetics.
- Afrezza — inhaled human insulin powder; onset 1 to 3 minutes, duration 1.5 to 3 hours. Useful for needle aversion but requires lung function testing and is not for asthma or COPD.
Short-Acting (Regular) Insulin
Regular human insulin (Humulin R, Novolin R) is the unmodified molecule. It is the cheapest mealtime insulin and is sold over the counter in most US states. Onset 30 to 60 minutes requires injection 30 minutes before meals. Duration 5 to 8 hours can cause delayed between-meal hypoglycemia. See Humulin R and Novolin R for details. Concentrated U-500 regular insulin is used for severe insulin resistance.
Intermediate-Acting (NPH) Insulin
Neutral Protamine Hagedorn (NPH) insulin is human regular combined with protamine to slow absorption. It is cloudy and must be resuspended. Onset 1 to 2 hours, peak 4 to 10 hours, duration 12 to 18 hours. Used as a basal in twice-daily dosing or as the basal component of 70/30 premixes. See Humulin N for details. Largely superseded by glargine and degludec for outpatient basal therapy because of its pronounced peak and hypoglycemia risk.
Long-Acting and Ultra-Long-Acting Basal Analogs
| Insulin | Brand | Onset | Duration | Notable Feature |
|---|---|---|---|---|
| Glargine U-100 | Lantus, Basaglar, Semglee, Rezvoglar | 1–2 h | 20–24 h | First long-acting analog; many biosimilars |
| Glargine U-300 | Toujeo | 2–6 h | 30–36 h | Lower hypoglycemia rate vs. U-100 |
| Detemir | Levemir | 1–2 h | 18–24 h | Often twice daily; albumin-bound |
| Degludec | Tresiba | ~1 h | >42 h | Most forgiving of dose-time variability |
See our deeper comparison of degludec vs. glargine for choosing between the two leading basals.
Premixed Insulins
- 70/30 NPH + Regular — Humulin 70/30, Novolin 70/30. Cheapest premix.
- Humalog Mix 75/25 — protaminated lispro + lispro.
- Humalog Mix 50/50 — for meals with larger carb loads.
- Novolog Mix 70/30 — protaminated aspart + aspart.
- Ryzodeg 70/30 — degludec + aspart, the first true basal + bolus premix with separate kinetics; flexible timing.
Choosing an Insulin: A Decision Framework
| Scenario | Typical Recommendation |
|---|---|
| New T1D adult | Basal-bolus: glargine or degludec + rapid analog with each meal |
| T1D with frequent hypoglycemia | Degludec basal + rapid analog, or pump with CGM |
| T2D with A1C 7.5–10% on max oral therapy | Add long-acting basal at bedtime; titrate to fasting target |
| T2D with A1C >10% at diagnosis | Basal + bolus or premix; consider GLP-1 RA add-on |
| T2D with consistent meals, wants fewer injections | Premix 70/30 or 75/25 twice daily |
| Pregnancy | Aspart or lispro + detemir or NPH (insulin choices in pregnancy are individualized) |
| Hospitalized hyperglycemia | IV regular insulin or basal + correction |
| Needle averse | Inhaled insulin (Afrezza) or pump consideration |
| Cost-constrained, uninsured | OTC human insulin (Humulin R + N or 70/30) |
Cost Snapshot (US, 2026)
| Insulin | Approx. List Price per Vial | OOP With $35 Cap |
|---|---|---|
| Humulin R, Humulin N, Novolin 70/30 (OTC) | $25–50 | n/a — already low |
| Lantus, Basaglar, Semglee | $150–300 | $35/month |
| Toujeo U-300 | $200–350 | $35/month |
| Tresiba | $200–350 | $35/month |
| Humalog, Novolog, Apidra | $150–300 | $35/month |
| Fiasp, Lyumjev | $200–350 | $35/month |
| Afrezza | $300–500 | varies |
Common Side Effects Across All Insulins
- Hypoglycemia — risk highest at peak; severity varies by type and dose
- Weight gain of approximately 2 to 4 kg in first 6 to 12 months
- Injection site reactions, lipohypertrophy from poor rotation
- Hypokalemia (low potassium)
- Rare anaphylaxis
- Fluid retention, especially with thiazolidinediones
Authoritative Sources
For full prescribing details on every insulin, see the FDA Drugs@FDA database. Clinical selection guidance is in the ADA Standards of Care in Diabetes 2024.
The Bottom Line
Insulin types are differentiated by onset, peak, and duration — and matching those properties to your meal pattern, activity, and glucose goals is the foundation of insulin therapy. Rapid analogs cover meals; long-acting analogs provide basal coverage; premixes simplify dosing at the cost of flexibility; inhaled insulin offers a needle-free option for selected patients. Most people with type 1 diabetes use basal-bolus or a pump; most people with type 2 diabetes start with a single long-acting injection and intensify as needed. Cost and access vary widely, but $35-per-month caps now apply to most US patients. Work with your clinician to choose the regimen that fits your physiology and your life.
