Advanced cancer and diabetes

If you have advanced cancer, managing diabetes may be more difficult. Your doctor, nurse, GP or diabetes team can offer you advice and support.

Advanced cancer

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

It is rare for advanced cancer to be cured. But people may live with it for a long time, sometimes for years. This may mean having different treatments when they are needed. It can also mean having ongoing treatment to control the cancer. During this time, many people carry on with their normal 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. If this happens, doctors use treatment to control the symptoms of cancer. The person may start seeing a team of healthcare professionals that specialise in controlling symptoms (palliative treatment). They are called a palliative care team.

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Managing diabetes and advanced cancer

Managing your diabetes can be more difficult if you have advanced cancer. You may be set more flexible blood sugar level targets. This is because you may have symptoms that can make it hard to manage your blood sugar level. These include:

People with advanced cancer are often less active than normal. This means their bodies use up less sugar. Advanced cancer can also change the way the body uses food, which can affect blood sugar level.

Some medicines used to help control cancer symptoms can affect blood sugar level. These include steroids and some painkillers. They can also affect the way that food is absorbed in the body.

Managing your blood sugar level when you have advanced cancer

When you are first diagnosed with advanced cancer, you may still be active and have a good appetite. At this time, your diabetes can usually be managed normally.

One of the main aims of managing diabetes is to prevent long-term complications. When you are having palliative treatment, this becomes less important. As you become more unwell, you do not have to be as strict with managing your blood sugar level. But having a very low or very high blood sugar level can cause upsetting symptoms. Your healthcare team will support you to keep your blood sugar level within a range to help avoid these symptoms.

You should always be involved as much as possible in any decisions about how your diabetes is managed. Your healthcare team will discuss with you and your family any changes to your diabetes management as your health changes. Your diabetes team, cancer team, GP and palliative care team can offer you advice and support. They can arrange more help if needed.

Changes to your diabetes medication

If you take insulin, you can keep checking your blood sugar. Or a carer can help you if you are not feeling well enough to.

If you have type 1 diabetes, insulin should never be stopped. But your healthcare team may suggest changing your insulin regimen. They will discuss this with you and your family. If you manage your diabetes with tablets, the type of tablet may be changed.

Towards the end of life

Towards the end of life, it is normal to start to lose energy. You may need to rest a lot during the day and may sleep most of the time. You may only be taking sips of fluid and not eating very much. At this time, there should be no restriction on what you eat. You also will not need to check your blood sugar level as often.

If you have type 1 diabetes, you will need to continue on your insulin. But your healthcare team may change you to a simpler regimen. If you have type 2 diabetes, your insulin may be stopped. But this decision will depend on your blood sugar level, symptoms and cancer treatment. Your diabetes team will discuss this with you. If you have been taking diabetes tablets, your diabetes team may recommend stopping taking them. They 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.

About our information

This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer.

  • References

    Below is a sample of the sources used in our diabetes and cancer treatment information. If you would like more information about the sources we use, please contact us at

    Joint British Diabetes Societies for inpatient care (JBDS-IP). The management of glycaemic control in people with cancer. 2023.

    Joharatnam-Hogan, N; Chambers, P; Dhatariya, K; and Board, R. The Joint BritishDiabetes Society for Inpatient Care (JBDS), UK Chemotherapy Board (UKCB). A guideline for the outpatient management of glycaemic control in people with cancer. Diabetes Medicine. 2022; 39.1-11. Available from: [accessed Oct 2022].

    Shahid, R.; Shahid, A.; Duc, L; and Sunil, Y. Diabetes and Cancer, Risks, Challenges, Management and Outcomes. MDPI. 2021;13:1-21. Available from: [accessed Oct 2022].

Date reviewed

Reviewed: 01 September 2023
Next review: 01 September 2026
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

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