Breast cancer diabetes
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Expert-reviewed by Ashwini S.Kanade, Registered Dietician and Certified Diabetes Educator with 17 years of experience

Diabetes and cancer are two of the most common diseases with tremendous impact on health worldwide. The association between type 2 diabetes and breast cancer includes the overlapping risk factors, such as obesity, a sedentary lifestyle, and high intake of saturated fat and refined carbohydrates. [1]

In fact, studies have shown a modest association between diabetes and the risk of breast cancer. This is more consistent in postmenopausal women than among premenopausal women. [2]

Let’s find out more.

Can Type 2 diabetes cause breast cancer?  

Dr S K Wangnoo Sr Consultant(Endocrinology), Indraprastha Apollo Hospitals says, “Type 2 diabetes does not cause breast cancer. However, there is an increased risk of breast cancer in hyperinsulinemia state (a condition where there is an excess of insulin in the blood compared to glucose).”

If there is a family history of breast cancer, one must go for a breast cancer checkup once every six months, according to Dr Malipatil. Also, he suggests, self-awareness regarding self-examination and region evaluation is a must, which includes:

  •         Checking of swelling of all or part of a breast (even if you don’t feel a distinct lump) Keeping a tab on skin irritation or dimpling
  •         Breast or nipple pain
  •         Nipple retraction (turning inward)
  •         Redness, scaliness, or thickening of the nipple or breast skin
  •         Nipple discharge (apart from breast milk)

Can cancer treatments cause diabetes?

“Effect of breast cancer treatment on diabetes is variable depending upon the type of medications used. In general, if the sugar rises during the treatment, the patient should be evaluated for diabetes. However, if the sugar settles down following the treatment, they should be evaluated for developing diabetes in future,” adds Dr. Wangnoo.

Effect of chemotherapy on blood sugar levels:

Dr. Baswantrao Malipatil, Consultant Oncologist, Columbia Asia Hospital, Whitefield, Bangalore, says, “Cancer and cancer treatment can bring about metabolic changes that can or might aggravate symptoms of diabetes. In fact, in chemotherapy patients, steroids are prescribed which can increase the glucose levels in blood markedly, causing variable effects on blood sugar levels.”

Chemotherapy has variable effects on blood sugar. Studies are suggesting that insulin might affect breast cancer risk and progression. [3]

Can radiotherapy treatment affect your blood sugar levels?

Radiotherapy is a procedure where high-energy rays, usually x-rays and similar rays (such as electrons), are used to treat cancer. While it is just known for destroying cancer cells, diabetics need to be extra careful. Even though cancer treatments cannot lead to diabetes, it is imperative for the high blood sugar to be aggressively managed during treatment.

“Generally, it is seen that during and immediately after radiotherapy, the blood sugar levels rise. Hence, it is crucial to test your blood sugar more often than usual pre and post the radiotherapy treatment,” says Dr. Wangnoo.

Preparing for surgery when you have diabetes:

If the doctor recommends surgery as part of your breast cancer treatment plan, then controlling your blood sugar levels becomes crucial. Uncontrolled diabetes may increase your risk during or after the surgery, the time taken to heal and also the chances of infection.

In the days before the surgery, talk to your doctor about how you can control your blood sugar levels. He might suggest changes in your medication, insulin dosage and even your diet and exercise routine to help prepare better.

If your blood sugar levels are not in control on the day of the surgery, your doctor might have to postpone or even cancel the procedure.


Preventive measures breast cancer survivors can take to reduce their risk of diabetes:

      • Lower your consumption of meat.
      • Lower or eliminate your white sugar intake.
      • Add more fibre to your diet in the form of green leafy vegetables, fruits, etc.
      • Increase your protein intake to help with recovery from breast cancer treatment. Ideally, these should be from vegetable sources as they are easily digested.
      • Eat foods with low glycaemic index since they help in maintaining the blood sugar levels.
      • Eat omega-3 fatty acids in many cases help in reduction of insulin resistance. They can also lower blood triglycerides, which are often high in insulin-resistant people.

Do note that a well-controlled diabetes management will have no complicating effect on cancer treatment.

“Only poorly controlled blood sugar levels can lead to short-term complications which can delay cancer treatment. But very rarely such instances are seen,” signs off Dr. Malipatil.



  1. Fei Xue and Karin B Michels. Diabetes, metabolic syndrome, and breast cancer: a review of the current evidence. 2007 American Society for Clinical Nutrition. Am J Clin Nutr September 2007 vol. 86 no. 3 823S-835S.
  2. Fei Xue and Karin B Michels. Diabetes, metabolic syndrome, and breast cancer: a review of the current evidence. 2007 American Society for Clinical Nutrition. Am J Clin Nutr September 2007 vol. 86 no. 3 823S-835S.
  3. Giovannucci, E., Harlan, D. M., Archer, M. C., Bergenstal, R. M., Gapstur, S. M., Habel, L. A., … Yee, D. (2010). Diabetes and Cancer: A consensus report. Diabetes Care, 33(7), 1674–1685.

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