Guide to Insulin Administration & Types

Insulin Administration Protocol

Insulin is a high-alert medication with a narrow therapeutic window. Errors in dosage or timing can lead to life-threatening hypoglycemia. Mastering insulin administration requires understanding pharmacokinetics—onset, peak, and duration—to match insulin activity with glucose intake. This guide outlines protocols for safe administration, designed to elevate your clinical practice.

The American Diabetes Association (ADA) emphasizes that effective glycemic control reduces microvascular complications. However, this goal must be balanced against hypoglycemia risk.

Pharmacokinetics of Insulin Types

Knowing the “Peak” time is critical as it represents the highest risk for hypoglycemia.

1. Rapid-Acting

Examples: Lispro (Humalog), Aspart (Novolog).
Onset: 15 minutes.
Peak: 1 hour.
Duration: 2-4 hours.
Nursing: “See food before you shoot.” Administer immediately before meals.

2. Short-Acting (Regular)

Examples: Humulin R, Novolin R.
Onset: 30 minutes.
Peak: 2-3 hours.
Duration: 3-6 hours.
Nursing: The only insulin suitable for IV administration. Used in DKA protocols.

3. Intermediate-Acting (NPH)

Examples: Humulin N, Novolin N.
Onset: 2-4 hours.
Peak: 4-12 hours.
Duration: 12-18 hours.
Nursing: Cloudy appearance. Must be rolled (not shaken) to mix.

4. Long-Acting (Basal)

Examples: Glargine (Lantus), Detemir (Levemir).
Onset: 3-4 hours.
Peak: No peak (steady state).
Duration: 24 hours.
Nursing: Do not mix with other insulins. Administer once daily.

Concentrated Insulins

Standard insulin is U-100 (100 units/mL). High-concentration formulas exist for severe insulin resistance.
U-500 Regular Insulin: 5 times more concentrated than U-100.
Safety: Use only U-500 dedicated syringes. Errors here cause massive overdose (5x intended dose).

Administration Techniques

Insulin is administered subcutaneously.

Injection Sites

• Abdomen: Fastest absorption. Preferred site. Stay 2 inches from the umbilicus.
• Arms: Posterior surface. Moderate absorption.
• Thighs/Buttocks: Slowest absorption.

Site Rotation

Repeated injections in one spot cause lipodystrophy (fatty lumps), impairing absorption. Rotate sites within the same anatomical region to maintain consistent kinetics.

Mixing Protocol: Clear Before Cloudy

When mixing Regular (Clear) and NPH (Cloudy):
1. Inject air into Cloudy (NPH).
2. Inject air into Clear (Regular).
3. Draw Clear (Regular).
4. Draw Cloudy (NPH).
Rationale: Prevents contaminating the rapid-acting vial with the long-acting modifier (protamine).

Hypoglycemia Management

Blood glucose < 70 mg/dL. Signs: Tremors, diaphoresis, tachycardia, confusion.

Rule of 15

• Consume 15g fast-acting carbs (4oz juice, 3-4 glucose tabs).
• Wait 15 minutes. Recheck glucose.
• If < 70 mg/dL, repeat.
• Once normal, eat a protein snack.

For unconscious patients, administer Glucagon IM or D50W IV. Refer to ISMP guidelines.

Insulin Pump Therapy

Continuous Subcutaneous Insulin Infusion (CSII) mimics physiologic pancreas function.
Basal Rate: Continuous small dose of rapid-acting insulin.
Bolus: Patient-activated dose for meals/corrections.
Nursing: Monitor for DKA if pump fails (no long-acting depot on board). Change infusion set every 2-3 days to prevent infection.

Sick Day Management

Illness raises blood glucose (stress response).
Protocol: Check glucose q4h. Check urine ketones if BG > 240 mg/dL. Do not stop insulin even if not eating (basal needs increase). Hydrate liberally.

Storage and Safety

• Unopened Vials: Refrigerator.
• Open Vials: Room temperature (28 days). Cold insulin causes injection pain.
• Safety: Never share pens. Use new needles. Double-check IV insulin settings.

FAQs: Insulin Therapy

Conclusion

Insulin safety is non-negotiable. By mastering pharmacokinetics, adhering to rotation protocols, and managing sick days, nurses ensure effective diabetes control. Vigilance prevents complications and empowers patient self-management.