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Insulin Timing

Published on Sep 14, 2015 and last reviewed on Jul 01, 2022   -  6 min read


Many patients suffer from hypoglycemia or low blood sugar after insulin treatment. In most cases, a lack of knowledge of insulin action is the cause. Read this article to know the onset and peak time of each type of insulin.

Insulin Timing

What Is Insulin?

The blood glucose level of the human body is controlled by a hormone called insulin secreted by the beta cells of the pancreas. These beta cells are contained in the islets of Langerhans. As a result, there is a build-up of sugar in the blood, and it is excreted in the urine. When there is not enough insulin produced in the body or if the insulin produced is not correctly utilized, it results in diabetes. Prolonged periods of increased blood sugar levels bring about serious complications.

Insulin produced by the beta cells is first called Proinsulin, a big molecule. This then breaks down into two molecules, namely Insulin and C-peptide. The insulin need of a particular person can be determined by measuring the level of C-peptide. An increased level of C-peptide indicates that the body produces an increased level of insulin.

There are two types of diabetes mellitus: type 1 and type 2. Of which, type 1 patients always require insulin to keep their blood sugar level in control. This is because the beta cells of these patients have been destroyed, and therefore, their pancreas cannot produce insulin. Although insulin production occurs in type 2 diabetes patients, utilization of the insulin produced is not good, so they require insulin. These patients are first treated with anti-diabetic medications, and if it is not effective, they are prescribed insulin injections.

Are Insulin Pills Available?

Extra-intestinal is the only route of administering Insulin because when taken orally, these are broken down like any protein during digestion.

How Is Insulin Administered?

Insulin can be self-administered by the patient itself and is usually given subcutaneously, in which it is injected into the subcutaneous fat tissues. These are then absorbed and released into the bloodstream.

How Many Times in a Day Is Insulin Given?

The treating doctor can only determine the number of times an insulin injection has to be administered for that specific individual. In general, a minimum of two insulin shots are required in a day for most diabetic people. At the same time, some may require three to four shots to keep their blood sugar under control.

When Should Insulin Be Taken?

Short-acting Insulins should be taken not more than 15 minutes before a meal. In the case of regular or long-acting Insulins, taking it 15 to 30 minutes before taking food is sufficient.

Is Monitoring Blood Glucose Level Needed?

Since low blood sugar level is an important complication of taking insulin, periodically monitoring the blood glucose level is essential. With the help of a glucometer, the blood glucose level is checked, recorded, and is shown to the treating doctor in the next visit so that the healthcare provider can decide on the dose of insulin. A glucometer is a device that helps measure blood glucose levels at home. When a drop of blood is placed on the strip inserted into the glucometer, the display rapidly shows the blood sugar value. This value is noted down.

What Is the Onset Time of Insulin Action?

It is the time taken for the insulin to begin lowering blood sugar levels. From the time the insulin is administered to the time, it takes to reach the bloodstream and start reducing the blood glucose level is the onset time.

What Is the Peak Time in Insulin Action?

It is the interval between the time of insulin administration and the time taken to exhibit the maximum strength of reducing blood glucose levels.

What Is the Duration of Action of Insulin?

The term duration denotes the time period of insulin action in the human body.

Are Inhaled Insulins Available?

Inhaled Insulins were made available in 2015, but these are not suggested to be an alternative for the conventional long-acting injectable Insulins and should only be taken along with it. These are rapid-acting Insulins that begin their action onset within 12 to 15 minutes, reach the peak value in half an hour, and are eliminated from the body within three hours.

What Are the Different Modes of Administering Insulin?

In addition to the conventional syringes used for administering insulin, there are also other modes of administration, which include:

Insulin Pens: An insulin cartridge is inserted into the pen. The units of insulin to be administered are dialed on the pen and administered like a conventional syringe. The cartridge can be changed with a new one if the insulin gets over.

Insulin Pumps: A catheter is placed under the skin, and the insulin is delivered through the catheter over a period of 24 hours.

What Are the Different Types of Insulin Preparations?

Insulin Preparation Generic Name Onset Peak
Rapid-acting Insulin Aspart 5-10 minutes

1-3 hrs

Insulin Lispro

< 15 minutes

½-1½ hrs

Insulin Glulisine

< 15 minutes

½-1½ hrs



½-1 hr

2-3 hrs

Intermediate-acting NPH

2-4 hrs

4-10 hrs

Long-acting Insulin Glargine

1 hr

No peak


1-2 hrs

No peak


70% NPH+30% Regular

½-1 hr

There are 2 peaks: 2-3 hrs &4-10 hrs

70% Aspart Protamine +30% Aspart

5-10 minutes

There are 2 peaks: 1-3 hrs & 4-10 hrs

50% Lispro Protamine +50% Lispro

< 15 minutes

There are 2 peaks: ½-1½ hrs &4-10 hrs

75% Lispro Protamine +25% Lispro

< 15 minutes

There are 2 peaks: ½-1½ hrs &4-10 hrs

How Is Insulin Administered?

  1. Insulin is injected with the help of a small needle, which helps administer the medicine into the subcutaneous tissues. Below are the steps involved in insulin administration:

  2. Wash your hands with soap and water.

  3. Pull the syringe plunger back to the marking equal to the number of units you have to administer insulin.

  4. Insert the needle into the rubber top of the insulin bottle and push the syringe plunger forward. While doing this, the air trapped in the syringe is released into the bottle.

  5. After ensuring that the tip of the needle is in contact with the liquid, pull back the syringe plunger to the point, you have to administer insulin.

  6. Make sure there are no entrapped air bubbles in the syringe. To remove air bubbles, if any, place the needle and the bottle in an upward position, tap the syringe, and look for any air bubbles that will be collected above. Push the plunger forward and remove the air bubbles.

  7. After removing the air bubbles, make sure you have the correct insulin dose in the syringe. If not, take the right unit of insulin by pulling the syringe plunger.

  8. Ensure the site where you have to inject the insulin is cleaned with cotton dipped in alcohol.

  9. Now, grab a skin fold and insert the needle at 90 degrees. In thin people, the needle can be inserted at 45 degrees.

  10. Insulin can be injected in the stomach, thighs, or arms. Of the above, the stomach has the fastest route of absorption, and the thighs show the slowest absorption.

What Is an Important Complication of Taking Insulin?

If the amount of insulin taken is more or if the person has skipped meals after taking insulin, it can result in hypoglycemia. Hypoglycemia presents the below symptoms:


Insulin plays a massive role in reducing and maintaining blood sugar levels in patients with diabetes. However, taking the insulin injection, increasing or decreasing its dose without the advice of a healthcare professional is not advisable and can result in serious complications. If you have diabetes, consult with a doctor, and only with their recommendation, start taking an insulin injection.

Last reviewed at:
01 Jul 2022  -  6 min read




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