Insulin is divided into 5 types: rapid-acting, short-acting (or fast acting), intermediate-acting, long-acting and pre-mixed insulin. The different types of insulin vary in the amount of time until they begin to work (onset), how long they take to achieve the greatest blood concentration and effectiveness (peak) and how long they continue to control blood sugar (duration). The effects of insulin, including onset, peak and duration times, vary from individual to individual and from day to day.
Depending on the brand, rapid-acting insulin has an average onset of from 5 to 15 minutes, peak of 30 minutes to 3 hours, and duration of 3 to 5 hours. It’s normally injected with meals, and used in combination with a longer acting insulin.
Short-acting insulin (also called regular insulin) has an average onset of 30 minutes to an hour, peak of 2 to 4 hours, and duration of 4 to 8 hours, depending on if it’s injected or used in an insulin pump. It’s taken 30 minutes to an hour before a meal, and may be combined with long-acting insulin.
Intermediate-acting insulin (also called NPH insulin or lente insulin) has an average onset of 2 to 4 hours, a peak of 4 to 10 hours, and duration of 10 to 18 hours. It’s often used in combination with rapid or short-acting insulin.
The effects of long-acting insulin (sometimes called background insulin or basal insulin) typically cover a full day. There are two types of long-acting insulin: insulin glargine (Lantus) and insulin detemir (Levemir). Typical onset for Lantus is within 4 to 6 hours. Lantus is delivered steadily and so does not peak, and has an average duration of 24 hours.
Typical onset for Levemir insulin is between 2 to 3 hours. Levemir peaks slightly between 8 to 10 hours, and the duration is dose-dependent, between 6 to 23 hours. Long-acting insulin is often used in combination with rapid or short-acting insulin, or an oral diabetes medication in the case of type 2 diabetics.
Premixed insulin is a combination of short and intermediate-acting insulin in the same vial or insulin pen. It’s normally taken twice a day before meals.