Insulin works differently depending on its type, brand, injection site, and individual factors. Here's a general overview of how long each type of insulin takes to start working for most people: **Rapid-acting insulin**: Starts working within 15 minutes and is usually taken right before a meal. Examples include lispro (Humalog) and aspart (NovoLog). **Short-acting insulin**: Takes effect within 30 to 60 minutes and is often taken 30 to 60 minutes before a meal. Examples include regular insulin (Humulin R, Novolin R). **Intermediate-acting insulin**: Begins to work in 1 to 2 hours and is used for half-day coverage. Examples include NPH insulin (Humulin N, Novolin N). **Long-acting insulin**: Takes effect in 1 to 2 hours and provides a steady level of insulin throughout the day. Examples include glargine (Lantus) and detemir (Levemir). **Ultra long-acting insulin**: Starts working in 6 hours and lasts for more than 24 hours. Examples include glargine U300 (Toujeo) and degludec (Tresiba). **Inhaled insulin**: Begins to work within 12 to 15 minutes and is taken just before a meal. An example is Afrezza. The absorption of insulin can be influenced by factors such as the injection site, physical activity, and smoking. The abdomen is the most effective site for rapid absorption, while the upper leg is the slowest. Always consult your doctor for personalized advice on insulin usage.