Advanced cancer and diabetes

Cancer can sometimes spread or come back after treatment. Treatment may help to control the cancer for a long time, but sometimes treatment isn’t possible or a person may not be well enough to have it. In these situations, treatment can often be given to help control the symptoms of cancer. This can make managing your diabetes more complicated.

The symptoms of advanced cancer can make it difficult to control blood sugar levels. These symptoms include:

  • loss of appetite
  • feeling sick
  • extreme tiredness (fatigue)
  • constipation or diarrhoea.

As you become more unwell, you don’t have to be quite as strict with controlling your blood sugar levels. But keeping your blood sugar within a good range is still recommended. You may need to adjust your diabetes treatment.

Towards the end of life, you may only be taking sips of fluid and not eating very much. There should be no restriction on what you eat and you won’t need to monitor your blood sugar level as often. Your diabetes medicines will be gradually reduced or stopped. Your diabetes team will help you with this.

Controlling the symptoms of cancer

Some people may have advanced cancer when they are first diagnosed. For others, the cancer may have spread or come back after treatment.

Although it is rare for advanced cancer to be cured, people may live with it for a long time – sometimes for years. This may mean having different treatments when they are needed, or sometimes having ongoing treatment to control the cancer. During this time, many people carry on with their day-to-day lives and keep doing things that are important to them. Sometimes it may not be possible to control the cancer any longer, or a person may not be well enough to have treatment. In this case, doctors use treatment to control the symptoms of cancer.

Trying to manage diabetes effectively can be complicated if you have advanced cancer. This is because you may have a range of different symptoms that can make it difficult to control blood sugar levels. This includes symptoms such as loss of appetite, feeling sick, extreme tiredness (fatigue), and constipation or diarrhoea.

Some medicines used to help control symptoms, such as steroids and some painkillers, can affect blood sugar levels or the way that food is absorbed in the body. People with advanced cancer are often less active than normal, so their bodies use up less sugar. Advanced cancer can also change the way the body uses food, which can affect your blood sugar level.


Controlling your blood sugar

When you are first diagnosed with advanced cancer, you may still be quite well. You may be active and have a good appetite. At this time, your diabetes can be controlled normally. The treatments you may have to help control advanced cancer may have fewer side effects than treatments given to cure cancer, but they may still affect your diabetes.

One of the main aims of successfully controlling diabetes is to prevent long-term complications. As you become more unwell, this aim becomes less important. You don’t have to be quite as strict with controlling your blood sugar level. But having very low or very high blood sugar levels can cause unpleasant symptoms, so keeping your blood sugar within a good range is still recommended.

As much as possible, you should always be involved with any decisions about how your diabetes is managed. Over time, your healthcare team can make changes to the doses of your diabetes medicines. These can be changed as your health changes. Your diabetes and cancer teams can offer your advice and arrange more help if needed.

If you use insulin to control your diabetes, you can keep monitoring your blood sugar and change your insulin dose if you need to. If you control your diabetes with tablets, the type of tablet may be changed or your doctor may suggest you start using insulin.

Towards the end of your life, it’s normal to gradually lose energy. You may need to rest a lot during the day and may sleep most of the time. You may be only taking sips of fluid and not eating very much. At this time, there should be no restriction on what you eat. You also won’t need to monitor your blood sugar level as often. If you are using insulin, the dose can be gradually reduced. If you have been taking diabetes tablets, they may be stopped. Your diabetes team will be able to help you with this.

We have more information about coping with advanced cancer. If you need more support, you can call our cancer support specialists for free on 0808 808 00 00.

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