Insulin questions are free points on the NCLEX — if you own one table and three rules. The exam doesn't test obscure brands; it tests whether you know when each insulin is working hardest, because that's when your client can crash.
The Only Chart You Need
| Type (examples) | Onset | Peak | Duration |
|---|---|---|---|
| Rapid-acting (lispro, aspart) | 10–15 min | 1–2 hrs | 3–5 hrs |
| Short-acting (Regular) | 30–60 min | 2–4 hrs | 5–8 hrs |
| Intermediate (NPH) | 1–2 hrs | 4–12 hrs | 12–18 hrs |
| Long-acting (glargine, detemir) | 1–2 hrs | None (flat) | ~24 hrs |
The Three Rules That Answer Most Questions
Rule 1: Regular is the only IV insulin
If a stem needs insulin in a drip or an IV push scenario, the answer is Regular. Everything else is subcutaneous only.
Rule 2: Glargine never mixes
Long-acting insulin goes in its own syringe, alone. When NPH mixes with Regular or rapid-acting, draw up the clear (short/rapid) insulin before the cloudy NPH — "clear before cloudy."
Rule 3: Hypoglycemia risk lives at the peak
A client who got NPH at 7 a.m. is most vulnerable around lunch. Rapid-acting given right before a meal demands that the meal actually arrives — a client who doesn't eat is a hypoglycemia setup.
A client receives NPH insulin at 7:00 a.m. When should the nurse be most alert for hypoglycemia?
- 8:00 a.m.
- 11:00 a.m. to 3:00 p.m.
- 7:00 p.m.
- The risk is equal all day
Show answer & rationale
Answer: B. NPH peaks 4–12 hours after injection, so a 7 a.m. dose peaks from late morning into the afternoon. At 8 a.m. the insulin is barely starting (onset 1–2 hrs), and by 7 p.m. it is wearing off. Peak = danger window, every time.
Frequently Asked Questions
Which insulin can be given IV?
Regular insulin only. Everything else is subcutaneous.
Which insulin never mixes?
Glargine (and detemir). With NPH mixes, draw clear before cloudy.
When is hypoglycemia risk highest?
At peak action — that's the window the exam keeps testing.
The Pharmacology Pack and 5,700-question Mega Bundle cover insulin and every high-alert med class with full rationales.
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