A nurse is preparing morning insulin for a 70-year-old clien… | MyMerci
Adverse Effects/Contraindications/InteractionsPA
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?
1Mix in the same syringe but inject within 2 hours to maintain efficacy.
2Draw both insulins into the same syringe in the order: air into glargine, air into regular, regular first, then glargine.
3Skip the regular and only give glargine because they cover the same period.
4Administer 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
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.