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Cancer and Diabetes: Is there a Connection?

By Margaret Martin, RD, MS, LDN, CDCES November 30, 2015Pearls of Wisdom Blog

November is Diabetes Awareness Month. In the news, there are hints that diabetes and certain types of cancers may be related. What is this relationship? If you have cancer, will you develop high blood sugar? Let’s explore some of these questions and more.

Let’s start at the beginning what is diabetes? Diabetes is a metabolism disorder. Metabolism is the internal process that allows your body to use food and nutrients and produce and use energy. A person with diabetes does not have adequate insulin in their bloodstream to enable glucose (sugar) to enter each cell in the body efficiently. Why does sugar need to enter each cell of the body? Sugar is the only component that cells can use for energy. Insulin is often referred to as the “key” that opens the cell to enable glucose to enter and be used for energy, metabolism, growth, and cell maintenance. Without the right amount of energy and insulin, the human body does not function at optimal performance– immunity can weaken and cognitive issues can arise.

Does eating sugar cause diabetes? Absolutely not! That is a misconception from thinking that high blood sugar results from eating too much sugar in our meals. Diabetes is a disorder of energy use in the body, not a sugar problem. If the body has frequently high levels of insulin in the circulating blood, that can cause other problems too like telling the body to store more fat.

Does sugar cause cancer? That’s a big question that can’t adequately be answered in this blog. (So check out this blog!) A quick explanation: if a person often eats foods with high amounts of simple sugars that consistently replace daily nutrient-rich foods (whole grains, lean protein, fruits, vegetables, dairy, etc.), the person can be at risk for inflammation, excessive body weight, and hormone changes. These risks can lead to increased risk for some cancers. It is best to eat well consistently and maintain a healthy body weight. Occasional desserts in moderation can be a part of an overall healthy diet as long as you continue to eat the proper amounts of whole grains, lean proteins, fruits, vegetables, and dairy. You can learn more about sugar and cancer.

The Oncology Nutrition Practice Group of the Academy of Nutrition and Dietetics has a great article on their website which gives insight into the diabetes and cancer relationship. The article reveals that cancer and diabetes occur in the same person more frequency than the medical word would predict. The exact relationship is not clearly known at this time. In fact, there is a consensus report on diabetes and cancer which further reveals “it remains unclear whether the association between diabetes and cancer is direct [e.g., due to hyperglycemia (high blood sugar levels)], whether diabetes is a marker for underlying biologic factors that alter cancer risk [e.g., insulin resistance and hyperinsulinemia (high insulin levels)], or whether the association between cancer and diabetes is indirect and due to common risk factor such as obesity.” (1) The report also reviews research that shows a relationship between diabetes and specific types of cancer such as liver, pancreatic, endometrial, colorectal, breast and bladder cancers.

If you have cancer, will you develop high blood sugar or diabetes? Answer: it depends. Having high blood sugar during cancer treatment doesn’t mean you did anything wrong so don’t beat yourself up about it. It may just be a side effect of your cancer treatment. After any surgery, including surgery for cancer, the body may allow blood sugar levels to increase while the body is trying to heal. Cancers in the body organs (such as the pancreas) that regulate insulin levels may increase the risk of high blood sugar and possible diabetes.

There is good news! There are treatments for high blood sugar, very effective treatments. Making better nutrition and lifestyle choices can also make a huge difference. Nutrition plans for high blood sugar are friendly and don’t focus on what you can’t have to eat. The nutrition recommendations can be tailored to your likes, dislikes, and food habits. Often, improved portion control and increased fiber intake go a long way to manage blood sugar levels. Get physically active, balance your carbohydrate intake with your meals and activity, take your medications consistently as prescribed, and ask for guidance from a practitioner experienced with diabetes like a Certified Diabetes Educator (CDE) who is also a Registered Dietitian Nutritionist.


(1) Giovannucci E, Harlan DM, Archer MC, Bergenstal RM, Gapstur SM, Habel LA, Pollak M, Regensteiner JG, Yee D. Diabetes and cancer: a consensus report. CA Cancer J Clin. 2010;60:207-21.

Margaret Martin, RD, MS, LDN, CDCES

Author Margaret Martin, RD, MS, LDN, CDCES

Nutrition Educator Margaret Martin is a Licensed Dietitian and Nutritionist in the State of Tennessee as well as a Certified Diabetes Educator. Margaret graduated from the University of Alabama with a Bachelor of Science in Dietetics and received her Master’s Degree in Nutrition Science & Public Health from the University of Tennessee. With more than 10 years of experience in Clinical Nutrition, Margaret has also worked in the insurance industry with WellPoint Inc. and Blue Cross Blue Shield providing telephonic nutrition consultations, service assistance, and web-based nutrition education. In her free time Margaret volunteers with the American Lung Association’s annual “Lung Force Walk" in Middle Tennessee. She belongs to the Oncology Nutrition & Diabetes Care and Education Dietetic Practice Groups of the Academy of Nutrition and Dietetics.

More posts by Margaret Martin, RD, MS, LDN, CDCES

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