Reference — Endocrine
Insulin Types Reference
Rapid-acting, short-acting, intermediate-acting, long-acting, and concentrated insulins — onset, peak, duration, appearance, and key nursing notes for all formulations.
Educational use only. Insulin selection, dosing, and timing are provider decisions; always verify against current orders, pharmacy guidance, and facility policy before administration. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
Insulin is a HIGH-ALERT medication. Verify dose with a second nurse per policy. Use only the appropriate syringe or pen for the concentration ordered. Never substitute brands without a provider order.
Appearance key: Clear = rapid-acting, short-acting (regular), and all long-acting insulins. Cloudy = NPH (intermediate-acting). When mixing clear + cloudy: always draw clear first, then cloudy(“clear to cloudy”).
Rapid-Acting
| Insulin | Onset | Peak | Duration | Clinical Notes |
|---|---|---|---|---|
| Lispro (Humalog) | 10–15 min | 1–2 hr | 3–5 hr | Give immediately before or up to 15 min after meals. Clear appearance. |
| Aspart (NovoLog) | 10–20 min | 1–3 hr | 3–5 hr | Give 5–10 min before meals. Used in insulin pumps. Clear. |
| Glulisine (Apidra) | 10–15 min | 1–1.5 hr | 3–5 hr | Give immediately before or within 20 min after starting a meal. Clear. |
Rapid-acting: give with meals. If patient cannot eat — HOLD and notify provider.
Short-Acting
| Insulin | Onset | Peak | Duration | Clinical Notes |
|---|---|---|---|---|
| Regular (Humulin R, Novolin R) | 30–60 min | 2–4 hr | 6–8 hr | Give 30 min before meals. ONLY insulin that can be given IV (drip or push). Clear appearance. |
Regular insulin: the only insulin for IV use. If mixing with NPH — draw up regular (clear) FIRST, then NPH (cloudy).
Intermediate-Acting
| Insulin | Onset | Peak | Duration | Clinical Notes |
|---|---|---|---|---|
| NPH (Humulin N, Novolin N) | 1–2 hr | 4–12 hr | 18–24 hr | CLOUDY — must be gently rolled (not shaken) before use. Given once or twice daily. Can be mixed with regular insulin. |
NPH = cloudy. Roll to mix. Do NOT shake. When mixing: clear before cloudy.
Long-Acting (Basal)
| Insulin | Onset | Peak | Duration | Clinical Notes |
|---|---|---|---|---|
| Glargine (Lantus, Basaglar, Toujeo) | 1–2 hr | No pronounced peak (peakless) | 20–24 hr | Once daily. Clear appearance despite being long-acting. NEVER mix with other insulins. Consistent injection time daily. |
| Detemir (Levemir) | 1–2 hr | Flat (6–8 hr mild peak) | 18–22 hr | Once or twice daily. Clear. DO NOT mix. Inject at same time each day. |
| Degludec (Tresiba) | ~1 hr | No peak (ultra-long) | >42 hr | Ultra-long-acting. Flexible dosing window (up to 8 hours before/after usual time). DO NOT mix. Clear. |
Long-acting basal insulins: NEVER mix with other insulins. Do not substitute brands without provider order (different concentrations).
Concentrated Insulin
| Insulin | Onset | Peak | Duration | Clinical Notes |
|---|---|---|---|---|
| U-500 Regular (Humulin R U-500) | 30 min | 4–8 hr | Up to 24 hr | 500 units/mL — 5× concentration of standard. Requires special U-500 syringe or pen. HIGH-ALERT. Never use standard U-100 syringe — fatal overdose risk. |
U-500 is an extremely high-alert medication. Always use U-500-specific pen or syringe. Never pull up in a U-100 syringe.
Timing Rules
| Insulin Type | When to Give | If Patient Cannot Eat |
|---|---|---|
| Rapid-acting (lispro, aspart, glulisine) | Immediately before meals (or up to 15 min after starting meal) | HOLD — notify provider. Risk of hypoglycemia without food intake. |
| Short-acting (regular) | 30 min before meals if SQ; immediately if IV | HOLD SQ dose — notify provider. IV infusion is different. |
| Intermediate-acting (NPH) | Usually AM ± PM — per provider schedule | Discuss with provider — may be reduced for illness |
| Long-acting (glargine, detemir, degludec) | Once daily at consistent time (some twice daily) | Generally continue — basal coverage regardless of eating |
Related Resources
Standards & sources
Fact-checked Jun 20, 2026This page is written to align with American Diabetes Association (ADA) Standards of Care · American Association of Clinical Endocrinology (AACE). It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →