What is the proper technique for administering insulin glargine subcutaneously?

How to Administer Insulin Glargine Subcutaneously

Insulin glargine must be injected subcutaneously once daily at the same time each day into the abdomen, thigh, upper arm, or buttocks, using proper rotation technique within each zone to prevent lipodystrophy. 1

Pre-Injection Preparation

Storage and Handling

• Unopened vials/pens: Store in refrigerator at 2-8°C (36-46°F) until expiration date 1
• Opened vials/pens: May be kept at room temperature below 30°C (86°F) or refrigerated for up to 28 days 1
• Critical: Allow insulin to reach room temperature 30-60 minutes before injection—cold insulin causes pain and contributes to lipodystrophy 2
• Never freeze; discard if frozen or exposed to extreme temperatures 1

Visual Inspection

Insulin glargine must be clear and colorless—this is a critical safety check. Do not use if cloudy, colored, or contains particles 3, 1. Unlike NPH or other intermediate-acting insulins that require resuspension, insulin glargine should never be shaken or rolled 3, 2.

Critical Mixing Rule

Insulin glargine must never be mixed with any other insulin or solution due to its low pH diluent 3. This is non-negotiable and distinguishes it from other insulin formulations.

Injection Site Selection

Approved Sites (in order of preference)

1. Abdomen (excluding 2-inch radius around navel) - preferred
2. Thighs (anterior and lateral aspects)
3. Buttocks
4. Upper arms (least preferred for self-injection due to difficulty achieving proper angle) 3, 2, 1

Systematic Rotation Protocol

Divide each body zone into quadrants or halves and use one zone per week, injecting at least 1 cm (one adult finger width) from the previous injection site, rotating in a consistent direction 2. This systematic approach—rotating within one area rather than jumping between different body regions—reduces variability in insulin absorption and prevents lipodystrophy 3.

Sites to Avoid

• Areas with lipodystrophy (pits or thickened skin)
• Localized cutaneous amyloidosis (lumps)
• Tender, bruised, scaly, hard, scarred, or damaged skin
• Areas with edema, infection, inflammation, or ulceration
• Through clothing (prevents proper technique verification) 2, 1

Injection Technique (Vial and Syringe)

Step-by-Step Procedure

1. Hand hygiene: Wash with soap and water or use alcohol 1

2. Verify insulin type: Check label—critical if using multiple insulin types 3, 1

3. Use U-100 syringe only: Wrong syringe concentration causes dosing errors 1

4. Prepare vial:

   • Wipe rubber stopper with alcohol swab
   • Do not shake or roll (unlike NPH insulin) 3, 1
   • Draw air equal to insulin dose and inject into vial 3, 1

5. Draw insulin:

   • Invert vial with syringe
   • Pull plunger to withdraw correct dose
   • Tap syringe to remove air bubbles; expel and redraw if needed 3, 1

6. Clean injection site:

   • Wipe with alcohol swab
   • Allow to dry completely before injecting 2

7. Inject:

   • Pinch skin and insert needle at 90° angle (most patients) 3
   • Thin individuals/children: use 45° angle or shorter needles to avoid intramuscular injection 3
   • Release pinch, slowly push plunger completely 1
   • Leave needle in skin for 10 seconds to ensure full dose delivery 1

8. Withdraw needle:

   • Pull straight out
   • Gently press site for several seconds (do not rub) 1
   • Never recap needle—increases needle-stick injury risk 3, 1

Timing and Dosing

Administer once daily at any time but at the same time every day 1. The 2025 FITTER guidelines emphasize consistency in timing for optimal glycemic control 2.

Disposal

Place used needles/syringes immediately in FDA-cleared sharps container or heavy-duty plastic container with puncture-resistant lid 3, 1. Never dispose in household trash unless local regulations permit.

Common Pitfalls to Avoid

1. Mixing with other insulins: Absolutely contraindicated due to pH incompatibility 3
2. Injecting cold insulin: Causes pain and lipodystrophy 2
3. Poor rotation technique: Leads to lipodystrophy affecting absorption 3, 2
4. Injecting through clothing: Prevents proper technique and site inspection 2
5. Using wrong syringe concentration: U-100 insulin requires U-100 syringes 1
6. Shaking the vial: Unlike NPH, glargine is clear and should not be agitated 3, 2
7. Removing needle too quickly: Wait 10 seconds to prevent insulin leakage 1

The most recent 2025 FITTER guidelines 2 provide the most comprehensive and updated recommendations, emphasizing systematic rotation, room temperature insulin, and proper site selection to optimize outcomes and minimize complications like lipodystrophy.