How immunotherapy can affect your diabetes

Immunotherapy is used to treat many different types of cancer.

Immunotherapy stimulates the immune system to kill cancer cells. This can affect blood sugar level. Your cancer doctor or specialist nurse can give you more information about the possible side effects of the drugs you are having.

Immunotherapy drugs that affect your blood sugar include:

The side effects of some drugs can be worse if you have diabetes. Your cancer doctor or specialist nurse can give you more information.

Immunotherapy drugs can cause high blood sugar levels in people who have diabetes. Rarely, they can cause diabetes in people who do not already have diabetes. If this happens, you may need diabetes medication.

It is important to tell your doctor or nurse straight away if you feel unwell or have any symptoms of high blood sugar. Occasionally, with some immunotherapy drugs, some people can develop ketoacidosis (DKA), which is a serious condition. Diabetes UK also have more information about high blood sugars and DKA.

Managing your blood sugar level when having immunotherapy

A course of immunotherapy treatment may last a few months, but some can last a few years. During treatment, you will need to check your blood sugar level more often. You may need to change your diabetes treatment. Your diabetes team or healthcare team will explain if you need any changes. For example, you may have to:

  • start using insulin as well as taking tablets
  • change the dose of insulin you take
  • start taking tablets if your diabetes is managed by diet.

It is important to tell your doctors how well you are managing your blood sugar level during your treatment. 

Talk to your cancer doctor or nurse if you do not have diabetes but develop any of its symptoms while having immunotherapy.

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 2026
Next review: 01 September 2026
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