🧪Types of Insulin
A complete clinical reference for all insulin types: onset, peak, duration, brand names, and when each is used. Essential knowledge for patients and clinicians starting or adjusting insulin therapy.
Why Different Types of Insulin Exist
The healthy pancreas secretes insulin in two distinct patterns: a continuous low-level basal secretion that runs 24 hours a day, and sharp mealtime boluses triggered by carbohydrate intake. No single insulin formulation can perfectly replicate both patterns, which is why insulin therapy typically uses at least two types of insulin — or a premixed combination.
Pharmacologists have engineered insulin analogs by making targeted amino acid substitutions in human insulin. These changes alter how quickly the insulin forms hexamers in solution (which must dissociate before absorption) and how it binds to insulin receptors — producing a spectrum of pharmacokinetic profiles from ultra-rapid to ultra-long-acting.
Rapid-Acting Insulin Analogs
Rapid-acting analogs are the gold standard for mealtime (bolus) dosing. They are engineered to dissociate quickly from hexamers into monomers at the injection site, enabling faster absorption than regular human insulin.
| Insulin | Brand | Onset | Peak | Duration |
|---|---|---|---|---|
| Insulin lispro | Humalog, Admelog | 10–15 min | 1–2 hr | 3–5 hr |
| Insulin aspart | NovoLog, Fiasp | 10–20 min | 1–3 hr | 3–5 hr |
| Insulin glulisine | Apidra | 10–15 min | 1–1.5 hr | 3–5 hr |
| Faster aspart (Fiasp) | Fiasp | 4 min | 60–90 min | 3–5 hr |
| Lispro-aabc (URLi) | Lyumjev | ~2–5 min | 45–75 min | 4–6 hr |
Dosing tip: Rapid-acting analogs are typically injected 0–15 minutes before a meal (or immediately after for those who are unsure how much they will eat). Their fast onset and shorter duration make them ideal for covering carbohydrate intake without excessive lingering insulin effect.
Short-Acting Insulin (Regular Human Insulin)
Regular human insulin (R) was the original injectable mealtime insulin, developed in the 1920s. It is still used today, though less commonly for mealtime dosing due to its slower onset compared to analogs.
| Insulin | Brand | Onset | Peak | Duration |
|---|---|---|---|---|
| Regular human insulin (R) | Humulin R, Novolin R | 30–60 min | 2–3 hr | 5–8 hr |
| Regular U-500 | Humulin R U-500 | 30–60 min | 2–4 hr | Up to 24 hr |
Because regular insulin must be injected 30–45 minutes before a meal for proper timing, it requires more advance planning than rapid-acting analogs. Regular U-500 (5× more concentrated) is used for patients with severe insulin resistance requiring very high doses.
Intermediate-Acting Insulin (NPH)
NPH (Neutral Protamine Hagedorn) insulin is a suspension of human insulin crystallized with protamine to slow its absorption. It provides an intermediate duration of action and is often used as a twice-daily basal insulin or in premixed formulations.
| Insulin | Brand | Onset | Peak | Duration |
|---|---|---|---|---|
| NPH (isophane) | Humulin N, Novolin N | 1–2 hr | 4–10 hr | 10–18 hr |
NPH's pronounced peak means it can cause nocturnal hypoglycemia if dosed at bedtime. It must be gently rolled (not shaken) to resuspend before use, as it has a cloudy appearance. Most modern basal therapy has shifted away from NPH toward peakless long-acting analogs.
Long-Acting Insulin Analogs (Basal)
Long-acting basal insulins are designed to be peakless — providing a smooth, steady supply of insulin over 20–42+ hours to replicate the pancreas's continuous basal secretion. They are the backbone of modern basal-bolus therapy.
| Insulin | Brand | Onset | Peak | Duration | Frequency |
|---|---|---|---|---|---|
| Glargine U-100 | Lantus, Basaglar | 2–4 hr | Peakless | ~24 hr | Once daily |
| Glargine U-300 | Toujeo | 4–6 hr | Peakless | ~36 hr | Once daily |
| Detemir | Levemir | 1–2 hr | Flat (mild) | 18–24 hr | Once or twice daily |
| Degludec U-100 | Tresiba | ~1 hr | Peakless | >42 hr | Once daily |
| Degludec U-200 | Tresiba U-200 | ~1 hr | Peakless | >42 hr | Once daily |
Premixed Insulins
Premixed insulins combine a fixed ratio of intermediate-acting (NPH) and rapid-acting (or regular) insulin in a single vial or pen. They can simplify regimens but offer less flexibility than separate basal and bolus injections.
| Product | Brand | Components |
|---|---|---|
| 70/30 | Humulin 70/30, Novolin 70/30 | 70% NPH + 30% Regular |
| 75/25 | Humalog Mix 75/25 | 75% NPL + 25% Lispro |
| 50/50 | Humulin 50/50 | 50% NPH + 50% Regular |
Biosimilar (Follow-On) Insulins
The FDA has approved several biosimilar insulins — products highly similar to their reference brand-name insulin in safety, efficacy, and purity, but typically lower in cost. Examples include:
- Semglee (insulin glargine-yfgn) — biosimilar to Lantus, FDA-designated interchangeable
- Rezvoglar (insulin glargine-aglr) — biosimilar to Lantus
- Admelog (insulin lispro) — biosimilar to Humalog
- Civica Insulin — a non-profit produced glargine, lispro, and regular insulin for $35/vial