# A nurse is preparing morning insulin for a 70-year-old client whose orders include insulin glargine 20 units AND insulin regular 8 units before breakfast. Which technique by the nurse is correct?

> source: MyMerci (mymerci.kr)  
> url: https://mymerci.kr/pages/nclex_q.php?qn_id=375039&lang=en  
> language: en  
> subject: Adverse Effects/Contraindications/Interactions  
> category: PA

## Question

A nurse is preparing morning insulin for a 70-year-old client whose orders include insulin glargine 20 units AND insulin regular 8 units before breakfast. Which technique by the nurse is correct?

## Option

1. Draw up the clear regular insulin first, then the clear glargine into the same syringe, and administer the mixed dose promptly to avoid precipitation, as both insulins are clear and short-acting regular insulin does not alter the long-acting profile of glargine.
2. Inject air equal to the glargine dose into the glargine vial, then air equal to the regular dose into the regular vial; withdraw the regular insulin first, then withdraw the glargine after gently rolling the vial to resuspend the precipitate, then inject subcutaneously.
3. Inject the glargine into the subcutaneous tissue first, leave the needle in place for 15 seconds to allow the glargine to form microprecipitates, then inject the regular insulin into the same site to prevent mixing in the syringe, which would alter the insulins' action.
4. Administer glargine and regular as TWO separate subcutaneous injections in different sites — long-acting insulins (glargine, detemir, degludec) must NEVER be mixed in the same syringe with any other insulin because mixing changes the absorption profile. **✔ Correct answer**

**Correct answer: 4**

## Explanation

Mixing rule for insulin
The cardinal rule: long-acting basal insulins (glargine, detemir, degludec) must NEVER be mixed in the same syringe with any other insulin. Mixing changes the pH and crystalline structure, altering absorption and unpredictably reducing both drugs effects.

What CAN be mixed:
• Regular + NPH: yes — proper sequence is air-into-NPH, air-into-regular, draw regular first then NPH (Clear-before-cloudy). Inject within 5-15 minutes (some sources say within 1 hour).
• Rapid + NPH (lispro/aspart + NPH): yes — many premixed products exist (Humalog Mix 75/25, Novolog Mix 70/30).

What must NOT be mixed:
• Glargine (Lantus, Toujeo): pH 4 — clear acid solution; mixing precipitates other insulins.
• Detemir (Levemir).
• Degludec (Tresiba).
• U-500 regular (concentrated; never mix; high-alert).

Standard practice: use SEPARATE syringes and inject in different sites (still rotate). Document each separately.

Skipping regular insulin (option 3) is unsafe — regular covers prandial glucose; glargine covers basal. They are not interchangeable.

## In-depth explanation

Clinical reasoning summary
Mixing rule for insulin
The cardinal rule: long-acting basal insulins (glargine, detemir, degludec) must NEVER be mixed in the same syringe with any other insulin. Mixing changes the pH and crystalline structure, altering absorption and unpredictably reducing both drugs effects.

What CAN be mixed:
• Regular + NPH: yes — proper sequence is air-into-NPH, air-into-regular, draw regular first then NPH (Clear-before-cloudy). Inject within 5-15 minutes (some sources say within 1 hour).
• Rapid + NPH (lispro/aspart + NPH): yes — many premixed products exist (Humalog Mix 75/25, Novolog Mix 70/30).

What must NOT be mixed:
• Glargine (Lantus, Toujeo): pH 4 — clear acid solution; mixing precipitates other insulins.
• Detemir (Levemir).
• Degludec (Tresiba).
• U-500 regular (concentrated; never mix; high-alert).

Standard practice: use SEPARATE syringes and inject in different sites (still rotate). Document each separately.

Skipping regular insulin (option 4) is unsafe — regular covers prandial glucose; glargine covers basal. They are not interchangeable.

## Related questions

- [A nurse is reviewing the morning lab results for an adult client receiving warfarin for at…](https://mymerci.kr/pages/nclex_q.php?qn_id=360515&lang=en)
- [A client is admitted to the emergency department after ingesting an unknown amount of acet…](https://mymerci.kr/pages/nclex_q.php?qn_id=362720&lang=en)
- [A client with chronic heart failure is prescribed metoprolol 25 mg orally twice daily. Bef…](https://mymerci.kr/pages/nclex_q.php?qn_id=362756&lang=en)
- [A 28-year-old client with type 1 diabetes receives regular insulin 6 units and NPH insulin…](https://mymerci.kr/pages/nclex_q.php?qn_id=362792&lang=en)
- [A client receives IV vancomycin 1 g every 12 hours for MRSA bacteremia. Before the next do…](https://mymerci.kr/pages/nclex_q.php?qn_id=362833&lang=en)
- [A client with bipolar disorder has been taking lithium carbonate 600 mg orally three times…](https://mymerci.kr/pages/nclex_q.php?qn_id=362894&lang=en)
- [An 80-year-old male with heart failure is prescribed digoxin 0.125 mg daily. During mornin…](https://mymerci.kr/pages/nclex_q.php?qn_id=372686&lang=en)
- [A 38-year-old female with rheumatoid arthritis is being discharged with a new prescription…](https://mymerci.kr/pages/nclex_q.php?qn_id=372687&lang=en)

## Read in another language

- [en](https://mymerci.kr/pages/nclex_q.php?qn_id=375039&lang=en)
- [ko](https://mymerci.kr/pages/nclex_q.php?qn_id=375039&lang=ko)
- [ja](https://mymerci.kr/pages/nclex_q.php?qn_id=375039&lang=ja)
- [zh-TW](https://mymerci.kr/pages/nclex_q.php?qn_id=375039&lang=zh-tw)
- [vi](https://mymerci.kr/pages/nclex_q.php?qn_id=375039&lang=vi)

---

More free questions: [NCLEX-RN Practice](https://mymerci.kr/pages/nclex_bank.php?lang=en)

_For study reference only. Always follow current clinical guidelines and your institution’s protocols._