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Insulin types cheat sheet: onset, peak and duration

Peak time is hypoglycemia time. Know when each insulin peaks and you know when your patient needs food on the tray and a glucose check.

This sheet covers the insulin types, how to mix them, and what to do for highs and lows.

✔ Reviewed by a licensed RN· Updated Oct 2026· Sources

InsulinOnset / Peak / DurationNursing move
Rapid (lispro, aspart, glulisine)10-30 min / 30 min-3 h / 3-5 h
  • Give 0-15 min before meals
  • Food must be in front of them
Regular (Humulin R, Novolin R)30-60 min / 2-4 h / 5-8 h
  • Give 30 min before meals
  • Usual IV insulin (drips, DKA)
NPH (Humulin N, Novolin N)1-2 h / 4-12 h / 12-18 h
  • Cloudy: roll, never shake
  • Evening dose: watch overnight lows
Glargine (long-acting)1-2 h / no peak / up to 24 h
  • Same time daily, basal
  • Never mix in a syringe
Degludec (ultra long)1 h / no peak / > 42 h
  • Once daily, flexible timing
Premixed 70/30, 75/25Analog 10-30 min, human 30-60 min / dual peak / up to 24 h
  • Before meals; cloudy
  • Do not add other insulin
Mixing ruleClear before cloudy (regular, then NPH)
  • Air into NPH first, then regular
  • Draw regular first, NPH second
Hypoglycemia < 70Cold, clammy, shaky, tachycardic, confused
  • 15 g fast carbs, recheck 15 min
  • Unresponsive: IV D50 or glucagon
HyperglycemiaHot, dry, polyuria, polydipsia, fruity breath
  • Check ketones if glucose > 240
Sites and rotationAbdomen fastest; rotate within one region
  • 1 in from scars, 2 in from navel; no massage
  • Exercise of the limb speeds uptake
Insulin and potassiumInsulin pushes K+ into cells
  • Watch for hypokalemia on IV drips
  • Why IV insulin + D50 treats hyperkalemia
Sick daysNever stop basal insulin
  • Glucose every 3-4 h, push fluids
  • Call: vomiting > 4 h, mod-large ketones, BG > 300 x2

RN pearl: Peak time is hypoglycemia time: teach the client to eat when their insulin peaks, and never mix glargine with anything.

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Frequently asked questions

When does NPH insulin peak?

4 to 12 hours after the dose, which is when hypoglycemia is most likely.

How do you mix regular and NPH insulin?

Clear before cloudy: inject air into the NPH vial first, then into the regular vial, draw up the regular, then the NPH.

Can glargine be mixed with other insulin?

No. Glargine is never mixed in the same syringe with any other insulin.

How do you treat hypoglycemia?

Give 15 g of fast-acting carbohydrate and recheck the glucose in 15 minutes. If the client is unresponsive, give IV dextrose (D50) or glucagon.

Keep studying

Lab values cheat sheetLab valuesNursing mnemonics cheat sheetStudy skills

Sources

  1. Pharmacology for Nurses, 28.2 Insulin and Non-Insulin Injectable Diabetes Drugs, OpenStax
  2. Medical-Surgical Nursing, 21.2 Diabetes Mellitus, OpenStax
  3. Clinical Nursing Skills, 12.5 Administering Subcutaneous Injections, OpenStax
  4. Sick Day Guide (2026), American Diabetes Association

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