Which of the following is an example of a rapid-acting insulin?

• A. Insulin lispro
• B. Insulin detemir
• C. Insulin glargine
• D. Insulin aspart

Answer: (A)

Rapid-acting insulins are used to cover the glucose rise after meals because they start working quickly and don’t linger long. Insulin lispro is a rapid-acting analog with a slightly altered structure that allows it to be absorbed faster after subcutaneous injection. This means it begins lowering blood glucose in about 10–15 minutes, peaks around an hour, and lasts roughly 2–4 hours, making it well suited to mealtime use.

The other options are long-acting, designed to provide a steady basal level rather than rapid post-meal coverage. Insulin detemir tends to have a longer duration with less pronounced peaks, while insulin glargine forms a slow-release profile that lasts about a day.