What Is Insulin?
Insulin is a hormone produced by the beta cells of the pancreas. Its primary function is to regulate blood glucose (blood sugar) levels by helping glucose move from the bloodstream into muscle and fat cells, where it can be used for energy or stored for later use. Insulin also helps regulate glucose production by the liver.
Types of Insulin
There are five major categories of insulin used to manage diabetes, classified according to how quickly they begin working and how long their effects last.
| Insulin type | Onset of action | Duration |
|---|---|---|
| Rapid-acting | 10–20 minutes | 3–5 hours |
| Short-acting (Regular) | 30–60 minutes | 5–8 hours |
| Intermediate-acting (NPH) | 1–2 hours | 12–18 hours |
| Long-acting | 1–4 hours | Up to 24 hours or longer |
| Ultra-long-acting | Approximately 1–6 hours | 36–42+ hours |
These are approximate ranges. Onset and duration vary by insulin formulation, dose, and individual response.