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What Are the Side Effects of Taking Insulin?

What Are the Side Effects of Taking Insulin?

What is Insulin?

Insulin is a natural hormone produced in the body. Man made or synthesized insulin is normally used as a medication in combination with an exercise program and diet plan to reduce high blood sugar levels in those with diabetes. Man made insulin replaces the functions of human insulin, which is to regulate blood sugar levels. There are many forms of insulin drugs that are used to treat people with diabetes. Diabetes refers to a chronic condition where a person does not produce enough insulin, or their body is not able to use it properly. Insulin is a naturally-occurring hormone which works by processing and absorbing glucose from the bloodstream body’s cells to use as energy. When you eat carbohydrate-rich foods, glucose is absorbed into the bloodstream. Glucose is a form of sugar, which is one of the greatest sources of fuel for the cells in the body. Without insulin, glucose cannot get into the body’s cells, thus they stay in the bloodstream. Too much blood sugar can lead to serious health complications, such as nerve problems, kidney damage, or blindness. People with diabetes are prescribed to use insulin medications to help them control their blood sugar levels. This medication works by helping glucose get into the muscle cells for energy. It also works by reducing the amount of glucose that is produced by the liver. This helps to reduce high blood sugar levels in people with diabetes. Insulin medication can be used alone or in combination with oral diabetes drugs like metformin.

Types of insulin

The different types of insulin medications vary in terms of how fast they start to work in the body and how long they work to reduce and control high blood sugar levels in your body. Your health care provider will prescribe the best type of insulin to treat your condition based on your individual needs. This will be based on how you respond to insulin medication, your age, and your goals for controlling your blood glucose levels. Insulin is classified in the following types:

Rapid-acting insulin

Rapid-acting insulin is commonly prescribed to people with type 1 diabetes. However, it can also be used by people with type 2 diabetes. Rapid-acting insulin is normally taken using an insulin pen or with an insulin pump. When injected under the skin, they start to work rapidly to reduce blood sugar levels. Rapid-acting insulin is normally taken before or with a meal. It acts by reducing the spike in blood sugar that usually follows eating. Examples of rapid-acting insulin include insulin lispro, insulin aspart, and insulin glulisine.

Short-acting insulin

Short-acting insulins are normally taken before eating, as well. Your doctor will advise you how long before a meal you should wait before using a short-acting insulin. Short-acting insulins do not work as fast as rapid-acting insulin in reducing blood sugar levels. An example of short-acting insulin is regular (or “R”) insulin, or Novolin.

Intermediate-acting insulin

Intermediate acting insulin is normally prescribed together with short-acting insulin. When injected under the skin, intermediate acting insulin starts to work within the first hour, and the effects can last up to seven hours. Intermediate-acting insulins include NPH or insulin isophane.

Long-acting insulin

Long-acting insulin is available in analogue and animal forms. This type of insulin usually takes the longest time before it starts to work in the body. When injected under the skin, the effects can last up to 24 hours, regulating blood glucose levels throughout the day. Long-acting insulin is also known as background or basal insulin. This is because they keep acting in the background to lower and control high blood sugar levels during the day. Examples of long-acting insulin include insulin glargine, insulin degludec and insulin detemir.

How to take insulin

Insulin comes in the form of a solution or suspension that is supposed to be injected subcutaneously. Before you use insulin, check whether it has changed color or has any solid particles in it. Insulin Regular is supposed to be clear and colorless. In case the color has changed or there are particles in it, you should not take this medication. Before you inject this medication, clean the site of injection using rubbing alcohol. Do not inject insulin into the same spot twice. Instead, change the site of injection each time to reduce the risk of lipodystrophy or other side effects. Your health care provider will show you the best places to inject your medication in your body. Insulin can generally be injected into the fat tissue of the stomach, buttocks, thigh or upper arm. You should not inject insulin into a vein or muscle since it may result in low blood sugar levels (hypoglycemia). Also, do not inject insulin into skin that is swollen, itchy or red.

Insulin is normally injected every day and your doctor may prescribe more than one type of insulin to be used. The insulin dose is usually determined based on your response to treatment and medical condition. Each dose should be measured carefully because even the slightest changes to your dose can affect your blood sugar levels. Your health care provider will tell you which type of insulin you should use and how many times per day you are supposed to take it. Do not change the insulin brand without your doctor’s advice. Make sure you follow your doctor’s instructions carefully. Use this medication regularly so that you can get the most benefit from it. As you take insulin medication, you may need to check your blood sugar levels regularly, or as directed by your doctor. Take note of your blood sugar levels and share the results with your doctor. This is important because It will help your doctor determine the right insulin dose for you. In case your blood glucose level is too high or too low, you should inform your doctor.


Opened and unopened insulin should be stored inside a refrigerator. Do not freeze insulin medication. In case of frozen insulin, you should not use it. Opened insulin vials can be stored in a refrigerator or kept in room temperature away from light and moisture. Opened insulin pens should be stored in room temperature. In case of expired insulin medication, it should be properly disposed. Ask your doctor how unused insulin should be disposed of.

Side effects

Insulin side effects among diabetic people is rare. Remember that your doctor prescribed insulin medication so that the benefit outweighs the risk. However, you may experience insulin side effects such as injection site reactions, with symptoms such as redness, irritation or pain. If this happens, you should stop taking the medication and inform your doctor immediately. Although rare, you may experience allergic reactions when you use insulin medication.

Symptoms of allergic reactions include

  • difficulty breathing
  • severe dizziness
  • rash
  • swelling in the tongue, throat and face
  • skin rash

If you notice any of these symptoms, you should seek medical help immediately. Taking insulin medication can also lead to hypoglycemia or low blood sugar levels. This may occur if you do not get enough calories from food or you exercise too heavily.

Symptoms of hypoglycemia include

  • fast heartbeat
  • dizziness
  • shaking
  • blurred vision
  • hunger
  • sweating
  • tingling feeling in feet or hands

It is important you carry glucose gel or tablets to treat symptoms of hypoglycemia. You can treat low blood sugar levels by taking fast acting carbohydrates such as hard candy, honey, table sugar or non diet soda.


Disclaimer: Please note that the contents of this community article are strictly for informational purposes and should not be considered as medical advice. This article, and other community articles, are not written or reviewed for medical validity by Canadian Insulin or its staff. All views and opinions expressed by the contributing authors are not endorsed by Canadian Insulin. Always consult a medical professional for medical advice, diagnosis, and treatment.
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