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Insulin Timing

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Insulin Timing

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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.

Medically reviewed by

Dr. Sneha Kannan

Published At September 14, 2015
Reviewed AtMay 10, 2023

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:

  • Dizziness.

  • Sweating.

  • Tiredness.

  • Confusion.

  • Difficulty in speaking.

  • Seizures.

  • Muscle twitching.

  • Loss of consciousness.


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.

Frequently Asked Questions


What Is the Best Time to Take Insulin?

The best time is to coordinate insulin intake with food consumption such that insulin starts functioning when glucose from food enters the bloodstream. So, the ideal time to inject regular (short-acting) and long-acting glucose is between 15 and 30 minutes prior to meals.


How Much Is the Time Gap Between Two Insulin Shots?

A rapid-acting insulin is administered every 3 to 5 hours, regular acting is administered every 8 to 12 hours, intermediate-acting must be administrated once to twice per day, and long-acting insulin typically must be administered once daily.


Will It Be Fine to Take Insulin After Food?

Insulin administration after meals may put one at a greater risk of low blood glucose or hypoglycemia. In case one misses an insulin dose, they should not panic but rather monitor the glucose levels.


How Much Time Gap Should Be There Between Insulin and Food?

Typically, between insulin shots and meals, 15 to 30 minutes should pass based on the type of insulin used. Short-acting insulins require a space of 15 minutes, while long-acting insulin requires around 30 minutes.


What Should Be the Sugar Level After Waking Up?

The sugar level in the morning after waking up can be referred to as the fasting blood sugar level (FBS). The typical range of FBS in a healthy individual varies between 70 to 100 mg/dl.


When Is the Sugar Level Highest in the Day?

Sugar levels are highest between 2 A.M. and 8 A.M. which is known as the dawn phenomenon or the dawn effect. This phenomenon is due to the release of various hormones in the body, like growth hormone, cortisol, and glucagon, which stimulate the liver to release glucose into the bloodstream.


How Do Peanut and Peanut Butter Affect Blood Glucose Levels?

Peanut and peanut butter consumption has been proven to diminish blood sugar spikes when paired with high-carbohydrate or high-GI foods (high glycemic index foods).


What to Drink Before Bed to Lower Blood Sugar?

Drinking warm water with one teaspoon of ACV (apple cider vinegar) can help control sugar levels in diabetic patients and manage fasting blood sugar levels (FBS).


How Does Fasting Affect Blood Sugar Levels?

Fasting can cause a decrease in sugar levels. Combining insulin with fasting can be detrimental as insulin can drop the glucose levels to a critical level and may result in a hypoglycemic diabetic coma. Further, monitoring sugar levels after breaking the fast are important as blood sugar levels are expected to be very high upon starting meals.


What Should Diabetics Eat for Breakfast?

Breakfast for diabetic patients may include food items like eggs, greek yogurt, berries, chia seed pudding, oats, multigrain bread, avocado spread, low-carb smoothies, wheat bran cereals, cottage cheese, fruits, nuts, peanut butter, or tofu.


How Do Coffee Affect Sugar Levels?

Coffee does not have any noticeable effect in non-diabetic individuals but causes a glucose spike in diabetic patients. Coffee consumption has also shown a higher spike in glucose levels after meals.


Which Fruits Are to Be Avoided by Diabetic Patients?

Although fruits are indicated in a diabetic diet, certain fruits have a higher than preferable sugar content and should be avoided in diabetic patients. The avoidable fruit list includes pineapples, cranberries, raisins, figs, tangerines, mangoes, cherries, kiwis, and lychees.


What Is the Life of Insulin Without Refrigeration?

Insulin can be left unrefrigerated between 59°F and 86°F for up to 28 days without any significant degradation and remain functional.


How Long Does Insulin Take to Act?

Based on the type of insulin, it acts between 15 to 30 minutes to enter the bloodstream and lower sugar levels. Rapid-acting insulins take 15 minutes, while long-acting insulins take around 30 minutes to work on sugar levels.


Why Could Insulin Not Lower Sugar Levels?

Insulin might fail to lower blood glucose levels due to inherited insulin resistance, where the body does not respond to insulin. Other reasons might be insufficient insulin administration or injecting damaged insulin.
Dr. Basheer Ahamed
Dr. Basheer Ahamed



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