Insulin therapy replaces or supplements endogenous insulin in patients with diabetes mellitus. Understanding the timing of insulin action is essential to synchronize doses with meals and prevent hypoglycemia.
Insulin Classification Table
- Rapid-Acting (e.g., Lispro, Aspart, Glulisine): Onset: 15 mins | Peak: 1-2 hours | Duration: 3-5 hours. Inject within 15 minutes of a meal.
- Short-Acting (Regular Insulin - Humulin R): Onset: 30-60 mins | Peak: 2-4 hours | Duration: 6-10 hours. The only insulin that can be given intravenously.
- Intermediate-Acting (NPH - Humulin N): Onset: 1-2 hours | Peak: 4-12 hours | Duration: 16-24 hours. Cloudy suspension; mix by rolling, do not shake.
- Long-Acting (e.g., Glargine, Detemir): Onset: 1-2 hours | Peak: None (flat profile) | Duration: 24 hours. Cannot be mixed with any other insulin in the same syringe.
Hypoglycemia Warning: The risk of hypoglycemia is greatest at the PEAK of insulin action. Monitor for sweating, shakiness, confusion, and tachycardia.
