Which insulin category peaks between 30 minutes and 3 hours?

• A. Short-acting
• B. Rapid-acting
• C. Intermediate-acting
• D. Long-acting

Answer: (B)

Understanding insulin action timing is essential for matching dosing to meals. The peak time is when insulin exerts its strongest glucose-lowering effect. Rapid-acting insulins start working about 10–30 minutes after injection and reach their peak around 1–2 hours, often described as roughly 30 minutes to 3 hours, with a short duration of about 3–5 hours. This peak window fits the 30 minutes to 3 hours range well, making rapid-acting insulin ideal for post-meal coverage. By contrast, short-acting insulin tends to peak later, around 2–4 hours, with a longer duration; intermediate-acting peaks even later, and long-acting has no distinct peak but provides a steady baseline. Therefore, the insulin category with a peak between 30 minutes and 3 hours is rapid-acting insulin.