💊 Pharmacology · Lesson 1 of 6 · 7 min

Insulin Peaks: When the Client Will Crash

🍬 Regular insulin peaks two to four hours after the shot. If you gave it at 0730, the hypoglycemia question on the exam happens at 1000, right before the client's lunch tray arrives.

💡 Key idea

Rapid peaks in 30 minutes to 3 hours, regular in 2 to 4, NPH in 4 to 12, glargine has no peak. Draw clear before cloudy. Hypoglycemia: 15 grams of carbohydrate, recheck in 15 minutes.

🧠 Why it matters

RAPID-ACTING (lispro, aspart, glulisine): onset 10 to 30 minutes, peak about 30 minutes to 3 hours, duration 3 to 5 hours; give within 15 minutes of a meal, and the meal must be there. SHORT-ACTING REGULAR: onset 30 to 60 minutes, peak 2 to 4 hours, duration 5 to 8 hours; the standard insulin for IV infusions. INTERMEDIATE NPH: onset 1 to 2 hours, peak 4 to 12 hours, duration 12 to 18 hours; cloudy, roll to mix. LONG-ACTING (glargine, degludec): no pronounced peak, lasting 24 hours or longer; never mix in a syringe with other insulins. When mixing regular and NPH, draw CLEAR before CLOUDY. HYPOGLYCEMIA (glucose under 70) shows as shakiness, sweating, tachycardia, confusion and hunger; if the client can swallow, give 15 grams of fast carbohydrate (4 oz juice or regular soda, glucose tablets), recheck in 15 minutes, repeat if still low, then a snack with protein; if unconscious, give IM or subcutaneous glucagon or IV dextrose, never oral. Rotate sites within one region, do not aspirate, and refrigerate unopened vials; an opened vial can stay at room temperature for about 28 days.

🏥 In the real world

🥪 A client receives NPH at 0800 and then refuses lunch because of nausea. The nurse recognizes the peak window of 4 to 12 hours and checks glucose at 1300: 58 mg/dL, sweaty and anxious. Juice, a recheck, crackers with cheese. The exam builds this exact question: the insulin's peak, the missed meal, and the time of day.

📌 Takeaways

Regular is the standard IV insulin; rapid-acting must be given with food in reach
Mixing: clear (regular) before cloudy (NPH); glargine never mixed
Hypoglycemia rule of 15: 15 g carbohydrate, recheck in 15 minutes

📖 Terms in this lesson

Peak (insulin): The time after a dose when a drug's effect is strongest; for insulin, the hour the client is most likely to go hypoglycemic.

Rule of 15: For hypoglycemia, give 15 grams of fast carbohydrate and recheck the glucose in 15 minutes.

TIRED (hypoglycemia signs): Tachycardia, Irritability, Restlessness, Excessive hunger, Diaphoresis: the early signs of low blood sugar, checked at insulin peak times and treated with 15 grams of carbohydrate.

Insulins by onset and peak: Rapid-acting (lispro, aspart) peaks 30 minutes to 3 hours after injection, regular in 2 to 4 hours, NPH in 4 to 12, and glargine or degludec has no peak; hypoglycemia is most likely at the peak, so a meal must be ready.

Glucagon: The rescue hormone for severe hypoglycemia when the client cannot swallow safely: 1 mg IM or subcutaneously (3 mg intranasally), then turn the client on the side because vomiting is common and feed carbohydrate once awake; it also treats beta blocker overdose.

✅ Test yourself

A client received regular insulin at 0700. At which time is the client at greatest risk for hypoglycemia?

0730
1500
1900
0900 to 1100

Answer: D · 0900 to 1100

Regular insulin peaks 2 to 4 hours after administration, so 0900 to 1100 is the highest-risk window.

When mixing regular and NPH insulin in one syringe, which step is correct?

Draw up the regular before the NPH
Draw up the NPH first, then the regular
Mix them in the NPH vial
Shake the NPH vial vigorously before drawing

Answer: A · Draw up the regular before the NPH

Clear before cloudy prevents contaminating the regular insulin vial with NPH. NPH is rolled, not shaken.

An unconscious client with diabetes has a blood glucose of 38 mg/dL. Which action is correct?

Hold all treatment until the client wakes
Place glucose gel inside the cheek and wait
Give 4 ounces of orange juice
Administer IM glucagon

Answer: D · Administer IM glucagon

Nothing goes by mouth in an unconscious client because of aspiration risk. Glucagon or IV dextrose is the treatment.

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