About diabetes and cancer

Diabetes is a condition where there is too much sugar (glucose) in the blood and not enough in the body’s cells. The amount of sugar in the blood is usually controlled by the hormone insulin. Insulin is made in a gland called the pancreas.

There are two main types of diabetes:

  • type 1 diabetes – the pancreas doesn’t make any insulin
  • type 2 diabetes – the pancreas doesn’t make enough insulin or the insulin doesn’t work properly.

The aim of diabetes treatment is to keep the amount of sugar in the blood as normal as possible. Different treatments are used depending on the type of diabetes you have.

Having diabetes can increase your risk of developing some types of cancer. And some types of cancer can increase your risk of developing diabetes. We don’t know exactly why this is. Some types of cancer and type 2 diabetes have some similar risk factors, such as being overweight.

You can reduce your risk of developing type 2 diabetes and cancer by:

  • keeping to a healthy weight for your height
  • eating a healthy diet
  • keeping active.

What is diabetes?

Diabetes is a condition where the amount of glucose in the blood is too high. Glucose is a type of sugar. Our bodies use sugar for energy.

When we eat, food is broken down in the stomach and the small bowel. This is so the different nutrients, including sugar, can pass into the blood. Normally, the hormone insulin controls the amount of sugar in the blood. It helps move sugar into the body's cells, where it is converted into energy. Insulin is produced in a gland called the pancreas.

If the pancreas stops making insulin, or doesn’t make enough, too much sugar stays in the blood. This is called hyperglycaemia. Sometimes insulin is produced but it doesn’t work properly. This is called insulin resistance.

The pancreas
The pancreas

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There are two main types of diabetes:

  • type 1 diabetes, where the pancreas doesn’t make any insulin
  • type 2 diabetes, where the pancreas doesn’t make enough insulin or the insulin doesn’t work properly.

Type 2 diabetes is a lot more common than type 1. About 9 in 10 people with diabetes (90%) have type 2.

Diabetes UK has a helpful video showing how diabetes develops and the ways it affects the body.


Causes and risk factors of diabetes

Type 1 diabetes is an autoimmune condition. This is when the body’s immune system attacks healthy parts of the body by mistake. In type 1 diabetes, part of the pancreas is attacked and destroyed. The pancreas is then unable to make insulin. We don’t know why the immune system does this.

Type 1 diabetes can happen at any age, but it is more common in children and young adults. It can sometimes run in families.

People can develop type 2 diabetes because of certain risk factors:

  • age – the risk of developing type 2 diabetes increases with age
  • genetics – your risk increases if you have a close family member (parent, brother or sister) with type 2 diabetes
  • weight – being overweight will increase your risk, especially if you have fat around your waist
  • ethnicity – people of South Asian, Chinese, African-Caribbean and black African origin are more likely to develop type 2 diabetes.

Some medicines used to treat other conditions can increase the risk of developing diabetes. This is called drug-induced diabetes. These medicines include steroids that are commonly used to treat cancer.


Signs and symptoms of diabetes

When too much sugar stays in the blood, our bodies cannot use it for energy. We try to find energy from other sources, such as fat stored in the body. Our bodies get rid of the extra sugar by passing it out in the urine. This can cause the following symptoms:

  • passing a lot of urine, especially at night
  • being really thirsty
  • feeling very tired
  • losing weight for no obvious reason
  • itching in the genital area or getting thrush a lot
  • cuts and wounds that take a long time to heal
  • blurred vision.

The symptoms of type 1 diabetes usually develop quickly. With type 2, the symptoms are usually less obvious and develop slowly over a number of months or years. This means that someone may not realise they have developed type 2 diabetes. Drug-induced diabetes can sometimes develop quickly.

Talk to your GP if you think you have symptoms of diabetes. But remember, these symptoms can be caused by many other conditions.


Treating diabetes

The aim of treatment is to keep the amount of sugar in your blood as normal as possible. This helps to manage symptoms and prevent complications developing later in life. Type 1 and type 2 diabetes are treated in different ways.


Type 1 diabetes

Type 1 diabetes is treated with insulin. Insulin is given by injections or with a pump. Keeping to a healthy weight, eating a balanced diet and being more physically active are also important.

Type 2 diabetes

Type 2 diabetes can be managed by:

  • making lifestyle changes, such as keeping to a healthy weight, eating a balanced diet and being more physically active
  • taking tablets and medicines that help to reduce the amount of sugar in the blood
  • taking insulin, but this is less common.

Many people with type 2 diabetes have a combination of treatments.


Diabetes and cancer risk

It’s estimated that about 1 in 5 people with cancer (20%) also have diabetes.

People with diabetes are more at risk of developing certain types of cancer. We don’t know exactly why this is.

Type 2 diabetes and some types of cancer have some similar risk factors. For example, being overweight increases the risk of developing diabetes and cancers of the gullet (oesophagus), bowel, breast, womb and kidney. Both diabetes and cancer are also more common in people as they get older.

People with type 1 diabetes have an increased risk of developing cancer of the:

  • cervix
  • stomach.

People with type 2 diabetes have an increased risk of developing cancer of the:

  • pancreas
  • liver (primary liver cancer)
  • womb (endometrium)
  • bowel (colon and rectum)
  • bladder
  • breast.

People with type 2 diabetes have a lower risk of developing prostate cancer. It is not clear why this is.


Cancer and risk of diabetes

Some types of cancer can increase your risk of developing diabetes. You are at a greater risk of developing type 1 and type 2 diabetes if you have:

  • cancer of the pancreas
  • primary liver cancer
  • bowel cancer.


Reducing your risk of cancer if you have diabetes

If you have diabetes, you can help to reduce your risk of developing cancer by:

  • keeping to a healthy weight for your height
  • eating a healthy diet
  • keeping active
  • not smoking.

We have more information to help you with these healthy lifestyle choices.

Diabetes UK also has some useful information to help you lead a healthy lifestyle.