Topic
Insulin basics
How rapid and long-acting insulin work, how long a dose keeps working, and what insulin on board really means.
How long does Humalog last? In your body and once opened
Humalog starts working in about 15 minutes and keeps going for 2 to 5 hours. What changes that, and why an opened pen lasts 28 days out of the fridge.
What is insulin on board? Active insulin, explained simply
Insulin on board (IOB) is the rapid-acting insulin still working in your body. How long it stays active, why it matters, and what insulin stacking is.