Insulin

Definition

Insulin is a peptide hormone produced by beta cells of the pancreatic islets of Langerhans. It lowers blood glucose by facilitating cellular glucose uptake, glycogen synthesis, and lipid storage.

Insulin Types

• Rapid-acting (aspart, lispro, glulisine): Onset 15 min, peak 1 to 2 hr, duration 3 to 4 hr. Give with or just before meals.
• Short-acting (regular): Onset 30 min, peak 2 to 4 hr, duration 6 to 8 hr. Give 30 min before meals. ONLY type for IV use.
• Intermediate (NPH): Onset 1 to 2 hr, peak 4 to 12 hr, duration 12 to 18 hr (cloudy appearance).
• Long-acting (glargine, detemir, degludec): Peakless, duration 24+ hr. Do NOT mix with other insulins.

Administration Rules

• Rotate sites; abdomen has most consistent absorption
• Storage: unopened in refrigerator; opened can stay room temp up to 28 days
• Mixing: clear (regular) before cloudy (NPH). 'RN' order
• Only regular insulin is IV-safe

NCLEX Relevance

Peak times = hypoglycemia risk. Clear before cloudy. Only regular IV.