When Do I Take Short Acting Insulin?

Insulin is a hormone that is produced by your pancreas and helps to regulate blood sugar levels in your body….(continue reading)

Insulin is a hormone that is produced by your pancreas and helps to regulate blood sugar levels in your body.

There are three main types of insulin: short-acting, intermediate-acting, and long-acting although there are other types too.

Short-acting insulin starts working within 30 minutes after injection, and its effects usually last for about three to six hours.

In this article, we will discuss the benefits and drawbacks of short-acting insulin, who can take it, and any potential side effects.

What is insulin?

Insulin is a regulatory hormone that helps the body use glucose, also called blood sugar, for energy. When you digest food or drinks, your body breaks them down into glucose and other nutrients.

Natural insulin is produced from beta cells in your pancreas and helps move glucose from your blood into your cells, where it’s used for energy.

If your body stops producing or reacting to insulin properly, it can lead to diabetes.

short acting insulin

Why do diabetics need insulin?

Diabetes, also called diabetes mellitus, is a condition where your body can’t properly use the insulin it produces, or can’t produce enough insulin which causes high blood sugar levels.

Type 1 diabetes is when your pancreas stops producing any insulin and you will need to take insulin to supplement your lack of insulin for the rest of your life.

Type 2 diabetes is when your cells lose their insulin sensitivity and stop reacting to it, also called insulin resistance, which allows your blood glucose levels to rise.

One of the main differences between the two types of diabetes is that type 2 diabetes can usually be prevented and the symptoms lessened with healthy lifestyle choices.

The other most common type of diabetes is gestational diabetes which occurs when you are pregnant but usually disappears after pregnancy.

If you have diabetes, monitoring of blood glucose levels is necessary as is making healthy lifestyle choices and taking insulin if necessary.

Over time, the complications of diabetes can damage your heart, kidneys, nerves, and eyes among other medical conditions such as diabetic ketoacidosis which is when your blood becomes too acidic.

How do I take insulin?

There are a few different methods of taking a dose of insulin.

The most common way is to inject the insulin under your skin with a needle and syringe, an insulin pen, or an insulin pump.

Inhalation is the newest method of delivering doses of insulin to your body via an inhaler from the brand Afrezza that is similar to an inhaler used for asthma.

Always make sure to read the insulin label for the correct insulin dosing.

Which method you choose to use for your diabetes is dependent on your preference, insurance coverage, and what your doctor thinks will work best for you.

What are the different types of insulin?

There are a number of different types of insulin and they are differentiated by how fast the insulin lowers your blood sugar (onset time), how long it takes the insulin to be the most effective (peak time), and how long the medication lasts (duration).

The different types of insulin include:


Rapid-acting insulin is the fastest-acting insulin and takes approximately 15 minutes for it to start lowering your blood glucose levels with the peak being around one hour after taking it.

These types of insulin have a shorter duration period of two to four hours and are typically taken before mealtime.


Short-acting insulin, also called regular-acting insulin, regular insulin, insulin regular, or human insulin, has an onset time of 30 minutes.

The peak of short-acting insulin is in two to three hours while the duration is three to six hours.

You normally take short-acting insulin about a half hour to an hour before a meal.


If you take intermediate-acting insulin you can expect an onset time of two to four hours with a peak between four to 12 hours.

The duration lasts 12 to 18 hours and is typically taken as a half-day dose or before going to sleep although it can be mixed with other types of insulin too.


Long-acting insulin has an onset time of about two hours with no specific peak time.

The duration is up to 24 hours which makes this type ideal if you want to have an even level of insulin in your body throughout the day and night and can be mixed with other insulin types.

Ultra long-acting

When you use ultra long-acting insulin you can expect an onset of six hours with no peak time and a duration of up to 36 hours.


Premixed insulin involves mixing two different types of insulin for a range of effects, usually short-acting and intermediate-acting insulins.

Due to a variety of combinations possible, the onset is anywhere from five minutes to an hour with a peak that varies depending on the medications used.

The duration is normally 10 to 16 hours and it is usually taken before breakfast and then again before dinner.

What are the benefits of short-acting insulin?

Short-acting insulin is the most common type of insulin prescribed and it’s great if you need to have multiple daily injections or an insulin pump.

It begins to work very quickly, giving you more control over your blood sugar levels.

How fast acting insulin works; PrimaryChildrens

What are the disadvantages of short-acting insulin?

You may have to take short-acting insulin multiple times per day to meet your daily insulin requirements which can be inconvenient.

You have to be careful about timing your meals around when you take your insulin and practice blood glucose control so that your blood sugar levels don’t drop too low.

Are there any side effects to taking insulin?

The most common side effect of taking insulin is low blood sugar levels, also called hypoglycemia. Symptoms of severe hypoglycemia include feeling shaky, sweating, fast heartbeat, and hunger.

You can treat the symptoms of hypoglycemia by eating or drinking a quick source of sugar such as fruit juice, hard candy, honey, or milk.

You can lower your risk of hypoglycemia by actively managing your blood sugar levels and increasing the frequency of glucose monitoring. 

Other less common side effects of insulin include weight gain and allergic reactions, which can also happen at the injection site if you are not using an inhaler.

Allergic reactions can cause shortness of breath, wheezing, fast heartbeat, and sweating.

If you have an allergic reaction to insulin, stop using it and call your doctor right away. If you think you or someone else is having a medical emergency, call 911 immediately.

How does my doctor prescribe which type of insulin I will take?

The type of insulin you take is based on a number of factors including when you need to have the insulin work, how long it needs to last, and if you’re using other diabetes medications.

Other factors include your age, how physically active you are, your diet, and your ability to manage your blood glucose levels. Please tell your doctor about any other drugs you may be taking to avoid any drug interactions.

Who can take short-acting insulin?

Short-acting insulin is typically prescribed if you have type 1 or type 2 diabetes. If you have type 2 diabetes, you may only need short-acting insulin as a more intensive treatment if you are not able to control your blood sugar levels with diet and exercise alone.

Short-acting insulin may also be used if you have gestational diabetes.

The most common types of short-acting insulin include Humulin R, Novolin R, and Velosulin R.

There are also several premixed insulins that contain short-acting insulins including:

  • Humulin 70/30
  • Novolin 70/30
  • Novolog 70/30
  • Humulin 50/50
  • Humalog mix 75/25

Talk to your doctor or diabetes care team about which one or combination of medications is best for your diabetes management.


Insulin is a hormone that is produced in the pancreas that uses your blood sugar as energy.

Short-acting insulin is a type of insulin medication that begins to work very quickly and has a short duration and is most commonly prescribed if you have either type 1, type 2, or gestational diabetes.

The main disadvantage of short-acting insulin is that you may have to take it more than once a day and there are also some potential side effects, such as episodes of hypoglycemia, weight gain, and allergic reactions.

If you have any more questions, please talk to your doctor or healthcare provider about which type of insulin is right for you.

References and Sources:


American Diabetes Association

Fact Checked and Editorial Process

Diabetic.org is devoted to producing expert and accurate articles and information for our readers by hiring experts, journalists, medical professionals, and our growing Diabetic.org community. We encourage you to read more about our content, editing, and fact checking methods here. This was fact checked by Jacqueline Hensler and medically reviewed by Dr. Angel Rivera. 

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