Diabetes

Insulin Administration — Pens, Syringes, and Pumps

2025-08-18 • Updated 2025-08-21

Insulin delivery is about two things: the insulin you use and how you deliver it. Get both right and day‑to‑day control becomes simpler and safer.

1 Insulin types (what’s in the pen/vial)

Availability and brand names vary by region. Check your local formulary.

• Ultra‑rapid/rapid‑acting (bolus): for meals and corrections.
  Insulins: lispro (Humalog**, Lyumjev**), aspart (NovoRapid/Novolog**, Fiasp**), glulisine (Apidra).
  Onset: ~5–15 min · Peak: ~1 hr · Duration: 3–5 hrs.
  Notes: “Faster” versions (Fiasp, Lyumjev) start earlier; some people still pre‑bolus.

• Short‑acting (regular human insulin):
  Insulins: Regular (Actrapid/Humulin R/Novolin R).
  Onset: ~30 min · Peak: 2–3 hrs · Duration: 6–8 hrs.
  Notes: Older profiles; can suit pumps in specific cases or mixed‑insulin regimens.

• Intermediate (basal):
  Insulin: NPH (Protaphane/Humulin N/Novolin N).
  Onset: ~1–2 hrs · Peak: 4–10 hrs · Duration: 12–18 hrs.
  Notes: Has a peak — higher hypo risk overnight if timing/dose off.

• Long/ultra‑long (basal): for background insulin.
  Insulins: glargine U‑100 (Lantus/Basaglar), glargine U‑300 (Toujeo), detemir (Levemir — availability varies), degludec U‑100/200 (Tresiba).
  Onset: ~1–2 hrs · Peak: minimal/flat · Duration: 20–42+ hrs (product‑dependent).
  Notes: Degludec and glargine U‑300 are flatter/longer; once‑daily for most.

• Premixed insulins:
  Examples: 70/30, 75/25, 50/50 (rapid or regular + NPH).
  Notes: Fewer injections but less flexibility; timing and carb matching matter.

• Concentrated formulations:
  Examples: lispro U‑200, degludec U‑200, glargine U‑300, regular U‑500.
  Notes: Same units, less volume; use only with matching pens/syringes.

2 Delivery options (how you take it)

Pens (disposable or reusable)

• Pros: accurate dosing in units, portable, fine needles (4–6 mm).
• How‑to: prime 1–2 units before first dose; lift skin fold if lean; inject at 90°; hold 10 seconds before removing.
• Change needles every use (or at least daily).
• Rotate sites: abdomen (fastest), outer thighs, upper buttocks, back of arms. Use a simple grid to avoid lipohypertrophy.

Syringes/vials

• Pros: cheapest, flexible for unusual doses.
• Needle length: usually 6–8 mm; same 90° rule; skin fold if needed.
• Mixing (if prescribed): draw clear (rapid/regular) before cloudy (NPH). Roll NPH gently to resuspend.

Pumps (CSII) and AID systems

• Pros: programmable basal rates, temporary basal for exercise/illness, precise micro‑boluses; with CGM + algorithm (AID), can reduce hypos and smooth nights.
• Cons: device on body 24/7, set changes, site failures = rapid ketone risk.
• Essentials: change infusion set every 2–3 days (sooner in heat); if high BGL + ketones, inject correction by pen/syringe and change set.

3 Dosing framework (quick map)

• Basal–bolus: long/ultra‑long basal once daily (sometimes split), rapid for meals/corrections.
• ICR (insulin‑to‑carb ratio): e.g., 1 unit per 10 g carbs.
• Correction factor (ISF): e.g., 1 unit lowers BGL by 2.5–3.0 mmol/L.
• Pre‑bolus: 0–20 min for rapid; shorter for ultra‑rapid.
• Exercise: reduce pre‑meal bolus and/or use temp basal; carry fast carbs.

4 Safety, storage, and “gotchas”

• Hypo plan: always carry 15–20 g fast carbs; recheck BGL after 15 min; follow with longer‑acting carbs if next meal >1 hr away.
• Illness/ketones: never stop basal; check ketones when high or unwell; hydrate; follow your sick‑day plan.
• Storage: unopened insulin in the fridge (2–8 °C). In‑use pens/vials at room temp (per product label, often 28–56 days). Avoid heat/freezing.
• Site rotation: prevents lumps and erratic absorption.
• Double‑check units: U‑200/U‑300 pens dose in units; don’t transfer insulin from pens into syringes.
• When to call for help: persistent highs with ketones, vomiting, drowsiness/rapid breathing; severe hypo (can’t swallow) → glucagon + emergency services.

Related Guides

• Blood Glucose Testing — How and When to Check
• Continuous Glucose Monitors (CGMs) vs Finger‑Prick Testing
• Emergency Actions — Hypos, Highs, and Ketones
• Understanding HbA1c and Why It Matters

References (plain text)

• Product information (local formularies), NDSS sick‑day/hypo resources, Diabetes Australia technique guides, ISPAD/ADA dosing principles.

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