Rapid Acting Insulin – What Are Your Choices?

rapid acting insulin choicesRapid acting insulin is 1 of 5 categories of insulin. The other types of insulin are short acting, intermediate acting, long acting and pre-mix solutions. The rapid acting typical use is to help process increased glucose levels during meal times.

The three main characteristics of the insulin are as follows. The onset is very quick, from as low as 10 minutes to 30 minutes. The peak effect ranges from 30 to 90 minutes, depending upon the brand used. The duration can be as little as 1 hour up to 5 hours.

Usually, a person will use short acting insulin around meal times and longer acting insulin (e.g., intermediate, long, pre-mix) for assistance with glucose processing throughout the day. Individual needs will vary, so your individual combination will vary.

The advantage of rapid acting insulin over short acting insulin is that it tends to work faster. This means that you can eat quicker after an injection (if not before).

Use Factors

Whether you need to use rapid acting insulin and how much will vary from person to person. Some factors that your doctor will look at will to determine your individual needs include the following:

Blood Glucose Management: What blood glucose processing needs to you need to accomplish? Are you open to giving yourself multiple injections per day? How
active are you in monitoring your blood glucose?

Lifestyle Issues: How much do you exercise? What foods do you eat? Do you control your diet well?

Age: What is your age?

Absorption Characteristic: How well, or not, does your body absorb or use insulin? Every person processes insulin differently.

All of these factors and more contribute to an insulin therapy regime. Unfortunately, not everyone is the same and some trial and error does occur. Also, as we get older, consume different foods, or increase or decrease our exercise level can all cause us to need to adjust our short acting (and longer acting) insulin therapies.

Brands of Short Acting Insulin

There are three major brands of short acting insulin in the United States. Here is a chart of these and their onset, peak and duration characteristics.

Humalog or lispro, by Eli Lilly, typically takes 15 to 30 minutes before it starts to work (onset) and react with your body. The peak time of this insulin is 30 to 90 minutes from when it is injected and will have the best effect on helping with what you have eaten. The duration of this insulin is anywhere from 3 to 5 hours. Basically, this means that it will continue to work for 3-5 hours, but will work best during the peak time period.

Novolog or aspart by Novo Nordisk is another major brand of rapid acting insulin. The onset time for this insulin is 10 to 20 minutes which means you can typically inject it closer to the time you are eating. The peak time for this insulin is 40 to 50 minutes from when it is injected. Meaning that this will be the best time for you to ingest the food you are eating and to have the insulin help to break it down. The duration of this insulin is 3 to 5 hours which is the same as humalog. However, it starts to work much faster, yet lasts the same amount of time.

Apidra or glulisine by Sanofi Aventis, is a third major brand of rapid acting insulin. The onset time for this insulin is 20 to 30 minutes, which is right around the average of all three brands of insulin. The peak or primary window for this insulin is 30 to 90 minutes, which gives you more time to eat and to plan your day, as opposed to the shorter peak of Novolog. However, the duration of this insulin is considerably shorter than the others as it will only last for 1 to 2.5 hours before it will no longer be effective. This means that you will have a much shorter time to eat essentially, than you would with the other two. Which could be a good or a bad thing depending on your schedule and they type of person you are when it comes to following a schedule.


Regardless of which insulin you use, remember that you will need to monitor your glucose levels and be aware of your eating and exercise habits. These factors, and the ones mentioned above, will contribute to achieving insulin therapy success. If you think short acting insulin is right for you, talk to your doctor for more details.

By Erich Schultz – Last Reviewed October 2012.