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Many people with diabetes must take insulin to stay healthy. However, insulin therapy can cause a range of side effects.

Insulin is a hormone that helps regulate the amount of sugar, or glucose, in the blood. Insulin has a counterpart called glucagon, a hormone that works in the opposite way.

The body uses insulin and glucagon to ensure that blood sugar levels do not get too high or low and that cells receive enough glucose to use for energy.

When blood sugar is too low, the pancreas secretes glucagon, which causes the liver to release glucose into the bloodstream. However, people with diabetes might need to take supplementary insulin to help keep their blood sugar levels within a normal range.

In this article, we look at the side effects, risks, and myths of insulin therapy and provide tips for taking insulin safely.

Side effects and risks

Insulin therapy
People with type 1 diabetes need to take insulin. However, it can lead to side effects.

Many different types and brands of insulin are available in the United States.

The side effects that a person might experience depend on the type of insulin they are taking.

Common side effects include:

Hypoglycemia when taking insulin therapy

Insulin shots cause the cells in the body to absorb more glucose from the bloodstream. As a result, taking too much or administering an injection at the wrong time may cause an excessive drop in blood sugar.

If a person’s blood sugar level drops too low, they may experience symptoms, such as:

  • dizziness
  • trouble speaking
  • fatigue
  • confusion
  • pale skin
  • sweating
  • twitching muscles
  • seizure
  • loss of consciousness

Having a strict insulin schedule is essential for keeping blood sugar levels within a healthy range. A doctor may prescribe insulins that act at different speeds to keep a person’s blood glucose levels more consistent.

People at risk of hypoglycemia should wear a medical bracelet stating their type of diabetes, plus other necessary information, such as whether they control their condition with insulin.

These bracelets provide information to first aiders and medical professionals in case a person becomes conscious.

Other possible complications of Insulin therapy

Insulin therapy complications
Using insulin may increase the risk of eye complications.

There is also the possibility that taking insulin will cause more severe side effects, although these are less common.

Fat necrosis may develop in people who regularly inject insulin. This condition causes a painful lumpTrusted Source to grow in the subcutaneous tissue, which is just below the skin’s surface.

A 2013 review compared insulin therapy with metformin treatment. Metformin is another glucose-lowering treatment for people with type 2 diabetes.

These researchers found that the insulin therapy group in the study had an increased risk of several complications, including:

Another review concluded that the risks of insulin therapy might outweigh the benefits for people with type 2 diabetes. The authors highlighted the following downsides of insulin therapyTrusted Source:

  • the need to increase the dose and complexity of the treatment plan over time
  • the increased risk of severe hypoglycemia
  • a higher possible risk of death
  • a potential increase in the risk of specific cancers, including pancreatic cancer

Who needs to take insulin?

Diabetes impairs insulin production by the pancreas and use of this essential hormone by the body. The condition causes high blood sugar levels.

However, not every person with type 2 diabetes will need to take insulin. People with type 1, on the other hand, will have to supplement their insulin supply for the rest of their lives.

There are three main types of diabetes:

  • Type 1 diabetes: Typically starts in childhood when a person does not produce enough insulin. Usually results from the body’s immune system attacking an otherwise healthy pancreas.
  • Type 2 diabetes: Can develop at any age but 45 yearsTrusted Source is the average age of onset. Either the pancreas does not produce enough insulin, or the body’s cells become resistant to its actions.
  • Gestational diabetes: Occurs during pregnancy and makes it harder for a woman’s body to respond to insulin. Typically stops after childbirth but increases a woman’s risk of developing type 2 diabetes.

Type 1 and type 2 diabetes are usually lifelong conditions. According to the Centers for Disease Control and Prevention (CDC), more than 30 million people in the United States have diabetes. Type 2 diabetes is the most common, accounting for 90–95 percentTrusted Source of those with diabetes.

Insulin delivery devices

People with type 1 diabetes require daily insulin therapy to maintain regular blood sugar levels. However, the exact treatment regimen will vary from person to person.

An individual can deliver their insulin to their body through a pump. This is a machine that provides the hormone through a port, removing the need for injections. Some pumps are automatic, while others require more user input.

Some individuals may need to supply two to four doses every day. Extra shots of rapid- or short-acting insulin may be necessary at mealtimes.

People also use injections, pens, and inhalers to take insulin.

Types of insulin

A doctor can help customize a safe and effective insulin therapy regimen for a person with type 1 diabetes. According to the American Academy of Family Physicians, there are several different types of insulin that people can use separately or in combination.

These includeTrusted Source:

  • Rapid-acting insulins that start to work within 15 minutes and can last around 3­–5 hours.
  • Short-acting insulins that take 30–60 minutes to start working and have a duration of 5–8 hours.
  • Intermediate-acting insulins that take 1–3 hours to start working but last 12–16 hours.
  • Long-acting insulins that start to work in about 1 hour and can last 20–26 hours.
  • Premixed insulins that combine a rapid- or short-acting insulin with a longer-lasting one.

A doctor will prescribe one of these insulins or a mixture alongside a carefully controlled schedule. Following this closely will reduce the risk of side effects and complications.

Learn about different types of insulin here.

Non-insulin treatments

People with type 2 diabetes can often manage their condition without insulin therapy.

Alternative treatment options include lifestyle and dietary changes and non-insulin medications, such as metformin. However, if a person is unable to control their blood sugar levels using these treatments, a doctor may recommend insulin therapy.

Women with gestational diabetes typically receive insulin, but they can also manage their diabetes with metformin. A doctor will explain the safest way to take these medications during pregnancy.

Myths about insulin therapy

According to the American Diabetes Association (ADA), several common myths surround the use of insulin therapy for people with type 2 diabetes.

People who take insulin may sometimes hear others make the following statements, but they have no basis in research or fact:

  • “Insulin can cure diabetes.” There is, at present, no cure for diabetes. However, insulin can help a person control its effects.
  • “It will cause disruption in your life.” While a course of insulin takes some getting used to, a person can enjoy a full and active life, as long as they stick to their insulin schedule.
  • “Insulin injections cause pain.” Many people have a phobia of needles. However, modern insulin pens cause almost no pain. People using pumps can avoid injections altogether.
  • “Insulin will increase the frequency of severe hypoglycemia.” While insulin can increase the risk of hypoglycemia, certain insulins can limit a sudden drop in blood sugar.
  • “Insulin causes weight gain for as long as a person uses it.” Insulin might increase weight at first, but this is not an ongoing effect. The body first needs to adapt to insulin supplementation.
  • “The injection site is not important.” Where on the body a person inserts a needle or pen determines the speed at which insulin has an effect. This can be vital after meals when quick drops in blood glucose levels reduce the impact of the food.
  • “Insulin is addictive.” Insulin is not an addictive drug and is vital for any person whose pancreas does not produce insulin.

Talking to a doctor should put someone’s mind at ease about any concerns or anxieties they have about insulin therapy.

Tips for taking insulin therapy safely

Insulin is a prescription medication. A person should speak to their doctor about:

  • choosing the right type of insulin for them
  • possible side effects or interactions with other drugs
  • self-administering insulin safely and effectively

People with type 2 or gestational diabetes should discuss with their doctor whether insulin therapy is the best choice for them.

They may be able to use other treatment options to control their blood sugar levels, such as non-insulin medications and lifestyle and dietary changes.

It is essential that people who need to take insulin monitor their blood sugar levels regularly. Taking too much or too little insulin can lead to side effects or complications.

Following the prescribed treatment schedule is also vital. It is essential not to miss a dose and take every dose at the right time.

Anyone who experiences side effects while taking insulin therapy should speak to a doctor. It is possible that another treatment plan or a different type of insulin may be more suitable for their needs and lifestyle.

A doctor can also advise on how to prevent or reduce specific side effects.


People with type 1 diabetes need to take insulin daily to control their blood sugar levels and remain healthy. However, this treatment can cause weight gain at the start of the course, and taking too much insulin can lead to hypoglycemia.

Many individuals with type 2 diabetes and gestational diabetes can use non-insulin medications and lifestyle changes to manage their condition without needing insulin.

When taking insulin, it is vital that people follow their treatment plan. Anyone experiencing side effects or complications while taking insulin should speak to their doctor, who can recommend other treatment plans or different types of insulin.

A doctor can also provide advice on how to prevent or reduce certain side effects.

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