Types of Insulin

Individuals with diabetes may be required to take one or more different types of insulin depending on their specific insulin requirements. The types vary based on how fast they start to provide insulin, when their peak period of action is and for how long insulin in supplied.  There are also possible combinations of insulin types that can be used to address immediate needs and longer term needs for the purpose of maintaining blood glucose levels.

The four types of insulin include rapid-acting, short-acting, intermediate- and long-acting insulin. Most insulin options are available both as a generic insulin option as well as in a brand name medication. Combinations of insulin also come premixed in cartridges for an insulin pen or in vials or bottles for use in a syringe or insulin pump device. For individuals with type 1 diabetes injectable insulin which can be provided through a syringe, pen device or insulin pump is the only form of insulin possible. Those with type 2 diabetes may be able to use oral medications that work with the body’s natural insulin, but they may also need manufactured insulin as well.

Insulin That is Rapid Acting

Insulin that is called rapid-acting can include several different brand and generic names. This insulin, as the name implies, begins to work the quickest once introduced to the body. Typically the onset for most people will be within 15 minutes and the peak period will be between 30 and 90 minutes. Depending on the individual rapid-acting insulin can have a duration in the body of between 3 to 5 hours. Activity level, health issues, stressors and metabolic factors will all influence the duration of this insulin.

Rapid-acting insulin can be combined with short-acting or intermediate-acting for different individuals. Rapid-acting insulin is most commonly used during the waking hours and is not prescribed for nighttime use. It is typically the insulin that is used with a meal, allowing immediate insulin to regulate blood glucose levels that spike immediately after food consumption. The combination with the longer duration insulin provides a consistent blood sugar regulation program for several hours after the meal, which will typically take the individual to the next meal of the day.

In studies of the effectiveness of insulin considered rapid-acting on different populations the results can vary. Studies show that elderly individuals with type 2 diabetes may benefit from use of rapid-acting insulin to deal with irregular eating patterns typical within the age group. Studies also showed that the rapid-acting insulin may have a faster onset in elderly individuals, which may have implications in prescription and patient education. 1

Insulin That is Short Acting

Short-acting insulin is generically known as insulin regular. It is one of the most common types of insulin prescribed and is found in combination with both rapid and intermediate-acting insulin. Short-acting insulin starts to work within a half hour to one hour after injection and has a duration in the body of five to eight hours. The peak time for this type of insulin is two to four hours, again depending on several factors.

Insulin that is short-acting insulin can be taken within a half hour to an hour of food consuption. For some people this is a good option as it allows time for blood testing and injection prior to eating. Some short-acting insulin analogues are seen to actually have a more complete ability to control HbA1c than actual human insulin. Use may also be beneficial in improving blood glucose levels post meals up to a two hour range. 2

Insulin That is Intermediate-Acting

The onset of intermediate-acting insulin is approximately one to three hours after injection with a peak action at approximately eight hours after use. As the name implies this type of insulin is active in the body for about 12 hours with some individuals having a duration of up to 16 hours. This insulin is usually prescribed for nighttime use and is also commonly used in insulin combinations to provide consistent regulation of blood glucose levels throughout the day or night.

Insulin That is Long-Acting

Long acting insulin begins working in about the same time as the intermediate acting insulin, which is approximately one hour after injection for most people. It works consistently throughout a 24 hour cycle, without a definite peak work time. For some individuals long-acting insulin can last up to 26 hours while others may find it is only effective for about 20 hours. This type of insulin mimics the small amount of insulin that the body continually produces, even between meals.

Recent advances in the use of insulin pumps or continuous subcutaneous insulin infusion has given diabetics another alternative for supplying insulin throughout the day. Research tends to indicate that for type 2 diabetes, either long acting insulin or insulin pumps may be appropriate options based on the individual patient, but for type 1 diabetes the use of continuous subcutaneous insulin infusion is still the preferred treatment option. 3

Insulin Combinations

Combinations of insulin options, including the rapid and short-acting and intermediate or long-acting insulin choices are usually injected twice a day, often before the first meal of the day and the evening meal or as determined by your physician. Depending on the specific type of insulin products used in the combination, the peak time for the product can be between 30 minutes to 12 hours after use and they can last for as long as 24 hours. Recently, many physicians are moving away from using these combination insulins and have been using long acting insulin in combination with rapid acting or short acting insulin for meals as this more closely mimics the body’s normal insulin production.

Factors That Influence Insulin Choice

There are several different factors that can influence the types of insulin or the insulin combinations that are most effective for blood glucose regulation. Factors such as lifestyle choices, food consumption, alcohol, tobacco use, exercise, health issues and the body’s unique response to the insulin will all be important factors to consider. Your age and overall health status will be critical as to how long the insulin continues to provide effective lowering of your blood sugar without additional insulin or dramatic changes in the blood glucose levels.

The number of times that you are willing to give yourself injections or the use of an insulin pump will also make a difference in the type of insulin that is most effective. Talking to your doctor about your insulin choices and the methods to administer the insulin is critical to give you the best possible combination for ease of blood glucose regulation. Your pharmacist may also be able to help answer questions regarding insulin use.


1 Krones, R., Schutte, C., & Heise, T. (2009). The rapid-acting properties of insulin aspart are preserved in elderly people with type 2 diabetes. Diabetes, Obesity and Metabolism , 41-44.

2 Mannucci, e., Monami, M., & Marchionni, N. (2009). Short-acting insulin analogues vs. regular human insulin in type 2 diabetes: a meta-analysis. Diabetes, Obesity and Metabolism , 53-59.

3 Pickup, J. C., & Renard, E. (2008). Long-Acting Insulin Analogs Versus Insulin Pump Therapy for the Treatment of Type 1 and Type 2 Diabetes. Diabetes Care , S140-S145.

This article was originally published July 12, 2012 and last revision and update of it was 9/10/2015.