Side Effects of Insulin Injections You Must Know

Dr. Pakhi Sharma (MBBS)
Dr. Pakhi Sharma (MBBS)

General Physician | 6+ years

insulin injection side effects
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For many people with Type 1 and Type 2 Diabetes, insulin can be a life-saving drug. But can insulin injections cause side effects? In this article, we will discuss the function of insulin in your body, how it works, types of insulin injections, the side effects, and precautions to be taken when under insulin therapy.
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    What is Insulin?
  • blog_single_bullet_icon
    Why is Insulin Prescribed?
  • blog_single_bullet_icon
    What are the Types of Insulin?
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    How Does Insulin Work?
  • blog_single_bullet_icon
    How to Use Insulin?
  • blog_single_bullet_icon
    Common Side Effects of Insulin
  • blog_single_bullet_icon
    Serious Side Effects of Insulin
  • blog_single_bullet_icon
    Precautions to be Taken While Administering Insulin Injections
  • blog_single_bullet_icon
    Myths About Insulin Therapy
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    When to see a doctor?
  • blog_single_bullet_icon
    Don’t Have Time To Read?
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What is Insulin?

Insulin is a hormone that is made by beta cells in your pancreas, a gland that is situated behind your stomach. Beta cells are unique cells in pancreas that synthesise, store and release insulin. Insulin helps the sugar (glucose) in your bloodstream to enter your cells, where it is used for generating energy and also stored for later.

In people with Type 1 Diabetes (a condition in which the body doesn’t make insulin) and in some people with Type 2 Diabetes (a condition in which the body doesn’t use insulin properly), synthetic insulin injections are used as a part of the treatment. However, the use of synthetic insulin can be associated with many side effects, ranging from harmless to life-threatening.

Why is Insulin Prescribed?

Insulin injections are prescribed for the management of both Type 1 and Type 2 Diabetes. The injected insulin acts as a replacement for, or a supplement to, your body’s natural insulin.

People living with Type 1 Diabetes produce little to no insulin in their bodies, so they have to rely on insulin injections to keep their blood sugar levels normal.

Most people living with Type 2 Diabetes can manage their blood sugar levels with oral hypoglycaemic medications and appropriate lifestyle changes. But for some individuals, their blood glucose levels remain high despite taking medicines, doing regular exercise, and diet control. For such people, insulin injections are prescribed to bring their blood sugar levels back to normal.

What are the Types of Insulin?

Insulin can be divided into categories based on factors like the source of insulin and duration of action.

Based on the source: 

  • Animal-sourced insulin: 

Derived from the pancreas of cows and pigs. This was the first type of insulin developed for human use, though it is rarely prescribed nowadays.
  • Synthetic insulin: 
Artificially synthesized in labs using recombinant DNA technology. This is the most widely used form of insulin.

Based on the duration of action:

Type of Insulin Onset of Action Peak Time Duration of Action
Rapid acting​
15 minutes
1 hour
2 to 4 hours
Regular/short acting
30 minutes
2 to 3 hours
3 to 6 hours
Intermediate acting
2 to 4 hours
4 to 12 hours
12 to 18 hours
Long acting
2 hours
Does not peak
Up to 24 hours
Ultra-long acting
6 hours
Does not peak
36 hours or longer
5 to 60 minutes
Peaks vary
10 to 16 hours
Source: Centers for Disease Control and Prevention (CDC)

How Does Insulin Work?

Regular human insulin (synthetic) is a man-made hormone with a chemical structure similar to natural insulin produced by the pancreas. For diabetics, this synthetic human insulin mimics the natural insulin produced in their body, and helps their cells use the glucose from food. It assists in controlling blood sugar levels and may help prevent diabetes complications.   

How to Use Insulin?

The dose of insulin injection to be taken is decided by your doctor based on the type and severity of your condition, your age and other associated medical conditions. Human insulin is usually administered subcutaneously (under your skin).

Your doctor will prescribe the frequency and type of insulin to be used. Regular or soluble insulin injection works best when taken 30 minutes before your meals. Human insulin solution may be injected intravenously (directly into the blood) by a doctor or nurse to lower your blood glucose levels in an emergency. It is recommended not to use more or fewer insulin doses than what your doctor prescribes.

Common Side Effects of Insulin

The most commonly observed side effects of insulin injections include:
  • Redness, swelling, pain, or itching at the site of injection
  • Changes in skin texture, dimpling or thickening of skin at the site of injection
  • Weight gain
  • Swelling of hands and feet

Serious Side Effects of Insulin

Insulin can cause some serious side effects if taken in higher doses than prescribed by your doctor. These include:

  • Hypoglycaemia: 

Too much insulin in your blood can cause your blood sugar levels to drop very low. Symptoms of hypoglycaemia include sweating, dizziness, shakiness, hunger, sleepiness, impaired vision, fatigue, lack of coordination, seizures or loss of consciousness. If left untreated, severe hypoglycaemia can cause coma or death.

  • Hypokalaemia:

Taking too much insulin can cause hypokalemia or low blood potassium levels. Hypokalaemia can cause constipation, muscle cramps, tiredness, breathing problems, irregular heartbeat, etc.

If you experience any of the above serious side effects, it is advisable to contact your physician immediately.

Precautions to be Taken While Administering Insulin Injections

It is important to take certain precautions if you are undergoing insulin therapy to avoid any adverse reactions.
  • Clean the site of injection before administration.
  • Make sure to rotate the sites of injection every day to prevent any skin reactions like thickening, dimpling, pain, redness, etc. 
  • Do not share your insulin pen or injection with others.
  • Store your insulin under the recommended conditions.
  • Do not take any other medications without consulting your doctor.
  • Avoid consuming alcohol as it can alter your blood sugar levels.  

Myths About Insulin Therapy

Some common myths and facts about insulin therapy include:

Myth 1: Insulin is not effective and does not work.

Fact: Diabetes is usually considered as a “sugar” problem, whereas it is actually an insulin problem. The human insulins used today are made to mimic natural insulin produced by your body. Research states that insulin is one of the best possible ways to reduce your blood sugar levels.

Myth 2: Insulin is addictive. 

Fact: Insulin is not a drug and you cannot get addicted to it. It is naturally produced by your body and is present in your bloodstream since birth. Insulin therapy only helps make up for the lack of natural insulin production in your body.

Myth 3: Taking insulin will drastically change your life.

Fact: It is a misconception that you will not be able to travel or live alone or eat away from home if you are taking insulin therapy. With proper planning and management, insulin can significantly improve your condition and quality of life for the better.

When to See a Doctor?

  • If you are planning to undergo surgery or have changed your eating or exercise habits, you need to see your doctor as you may require a change in your insulin dosage.
  • If your blood sugar levels remain high even after taking insulin, consult your doctor immediately.
  • If you are experiencing intense hunger, thirst, pain, tingling in the hands or feet, or any other signs of hypoglycaemia, contact your doctor immediately or seek emergency medical attention.
  • If you have fallen ill or feel sick, contact your doctor as you may need a change in your insulin dosage.

Don’t Have Time To Read?

  • Insulin is a hormone made by your pancreas, that regulates your blood sugar levels.
  • In individuals with diabetes, man-made or human insulin is prescribed (usually in the form of injections) to control blood sugar levels when the body is unable to produce or use insulin properly.
  • Being chemically similar to natural insulin, it helps in utilising the glucose in food to generate energy and store it for later use.
  • Insulin therapy may cause common side effects such as redness, swelling, or itching at the site of injection, weight gain, changes in skin texture at the site of injection, etc., and severe side effects such as  hypoglycaemia, hypokalaemia, etc.
  • Certain precautions like cleaning and rotating the injection site, proper storage of insulin, limiting alcohol consumption, etc., should be taken into consideration while under insulin therapy.
  • Several common myths revolve around the use of human insulin, including that it is ineffective, addictive and painful.
  • Use the Phable Care App to consult India’s leading diabetologists, order medicines, book lab tests, integrate blood sugar monitoring and other devices to get real-time remote care from the comfort of your home. Also, check out our Diabetes Management program which provides ‎360º care. Let’s treat diabetes together.

Frequently Asked Questions

Insulin is required to control  high blood sugar levels in diabetics. It is perfectly safe when taken with proper precautions and in the recommended dosage. However, it can cause some common side effects such as  itching, redness, swelling at the injection site, weight gain, etc. 

Insulin injections may cause changes in skin texture, rashes or swelling at the injection site. Initially, insulin injection may also cause weight gain in some patients. Hypoglycemia, anxiety, or depression are some of the other side effects of insulin injections.

Long-term use of human insulin may cause serious side effects such as fat redistribution under the skin at injection sites, low blood potassium levels, increased risk of heart problems, hypertension, etc. Contact your doctor right away if you are on insulin therapy and are feeling unwell. Your doctor may recommend frequent check-ups or tests to make sure you do not develop any complications or side effects.

In Type 1 Diabetics, insulin injection is the only recommended treatment. In Type 2 Diabetics, insulin therapy is prescribed when oral hypoglycaemic medicines (tablets) alone are not sufficient to bring down blood glucose levels.

Insulin is a hormone that is naturally found in the body. Hence it does not cause any damage to your kidneys or other organs.

When diabetics cannot control their blood sugar levels with exercise, weight loss, oral medications, and dietary changes, doctors recommend initiating insulin therapy to control elevated blood sugar levels.

Insulin and metformin have different functions/effects when administered. Metformin helps your cells and tissues utilise the insulin present in your bloodstream. Insulin injections supplement the natural insulin in your body and help your cells make use of the glucose (sugar) present in your blood.

Foods rich in soluble fibres such as flaxseeds, oatmeal, legumes, vegetables, fruits like oranges, and other foods like fenugreek seeds, ginger, garlic, turmeric, etc., help increase the insulin sensitivity in your cells and tissues.

Initially, insulin injections can be taken for several days or weeks, as per your doctor’s advice. Once your blood sugar reaches the targeted levels, your doctor may advise a reduction in insulin dosage and switch to oral hypoglycemic drugs, in type 2 diabetes. Insulin injections are an important part of type 1 diabetes treatment and cannot be stopped. 

Dr. Pakhi Sharma
Dr. Pakhi Sharma, MBBS
(General physician, 6+ years)
An expert in obstetrics and medical emergencies, Dr. Pakhi Sharma, an alumni of Sri Devaraj Urs University of Higher Education and Research Centre, is a general physician working at Phablecare. She has 6+ years of work experience spread across gynaecology and obstetrics, family medicine, and medical emergencies at renowned hospitals and clinics.

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