Insulin Administration and Timing is a high-stakes procedure where errors cause immediate harm. Nurses must match insulin type to its pharmacokinetic profile: rapid-acting (lispro, aspart, glulisine) — onset 15 min, peak 1–3 hours, given with food present or immediately before eating; intermediate NPH — peak 6–12 hours, given twice daily, late hypoglycemia risk overnight; long-acting (glargine, detemir, degludec) — no peak, once daily, DO NOT confuse with rapid-acting. Critical safety rules: hold rapid-acting insulin when glucose is below threshold or the patient cannot eat; verify insulin type and dose against orders (insulin is a high-alert medication requiring double-check); never mix glargine with other insulins; NPH is the only insulin that can be mixed with rapid-acting in specific ratios per order. Boards test: the correct action when a patient refuses the meal after rapid-acting insulin is given (treat for potential hypoglycemia immediately); identifying which insulin type requires food; and the nurse's responsibility to hold and report when an NPO patient has scheduled rapid-acting insulin ordered without a protocol.