Students memorize the insulin chart as a list of numbers. Nurses use it to answer one question: when is this patient most likely to bottom out? That’s the peak. Here’s the chart, then why it matters.

The four types

Times are approximate and vary by reference and product. Use your drug reference for exact numbers.

• Rapid-acting (lispro/Humalog, aspart/Novolog): onset about 15 minutes, peak about 1 to 2 hours, lasts about 3 to 5 hours. Give it with the meal tray in front of them.
• Short-acting (regular insulin): onset about 30 to 60 minutes, peak about 2 to 4 hours, lasts about 5 to 8 hours. The only one you’ll routinely see IV.
• Intermediate (NPH): onset about 1 to 2 hours, peak about 4 to 12 hours, lasts about 12 to 18 hours. Cloudy. Roll it, don’t shake it.
• Long-acting (glargine/Lantus, detemir, degludec): onset about 1 to 2 hours, little to no peak, lasts about 24 hours or more. Basal insulin. Don’t mix it with anything.

Why the peak matters

If NPH is given at 0700, its peak lands in the afternoon. That’s when you watch for low blood sugar, and it’s why that patient needs lunch. Exam questions love “when is the client most at risk for hypoglycemia?” Find the peak.

Mixing regular and NPH

Clear before cloudy. Inject air into the NPH first, then into the regular, then draw up the regular, then the NPH. That keeps cloudy insulin out of the clear vial.

Hypoglycemia: know it cold

• Signs: shaky, sweaty, fast heart rate, confused, irritable. (Remember beta blockers can hide the shaky and fast-heart-rate part.)
• Awake and can swallow: 15 grams of fast sugar, recheck in 15 minutes. That’s the “rule of 15.”
• Can’t swallow safely: IV dextrose or glucagon per protocol.

The safety stuff they’ll test

• Insulin is a high-alert drug. Many facilities require an independent double check.
• Never write “U” for units. Write it out.
• Rotate sites within the same area to avoid lumpy tissue.

Study aid only. Always follow your program, your facility’s policies, and a current drug reference.