Navigating Diabetes and Breast Cancer Treatment

Elizabeth Halprin, M.D., director of Adult Diabetes at Joslin Diabetes Center

October is National Breast Cancer Awareness month, and it’s estimated that one in eight women will be affected by the disease in their lifetime. It’s also estimated that about one in ten women will be diagnosed with diabetes.

When the diseases go hand-in-hand, many women share a common challenge: They struggle to balance cancer treatments with diabetes self management.

“Women diagnosed with breast cancer might tend to put diabetes lower on their list of priorities because their breast cancer is a greater concern in that moment, which is understandable, but trying to keep diabetes under control during this difficult time will actually help in dealing with the cancer and its treatment as well,” says Elizabeth Halprin, M.D., director of Adult Diabetes at Joslin Diabetes Center. “It’s critical to have excellent glycemic control, because that will help with the healing process and prevent complications of cancer treatment.”

Breast cancer treatment, whether it is surgery, radiation or chemotherapy, brings about changes that affect glucose metabolism, healing, weight, appetite and the way the body absorbs food.

When a woman starts chemotherapy, she may lose her appetite and stop eating healthfully, or stop eating altogether, which can cause her to develop hypoglycemia.

Another issue to be aware of, Dr. Halprin says, is that many medications are either mealtime based, particularly insulin, or designed to lower your blood glucose. So if you’re not eating a whole meal because of nausea or vomiting, your blood glucose level will drop too low.

Also complicating matters, cancer treatments cause crippling fatigue, which can make even light activity impossible. As a result, if you’re used to being very active and suddenly stop, your blood glucose level will likely go up.

Other things that raise blood glucose levels during treatment for cancer are emotional stress, physical stress and complications that may come up like infections.

Here’s what you can do to control diabetes while undergoing cancer treatment:

Work closely with your health care team.  Drugs used to treat cancer can cause blood glucose levels to fluctuate markedly. “Before beginning treatments, it is very important to coordinate with your diabetes providers to adjust your diabetes medications based on the course of cancer treatment you will be getting,” says Dr. Halprin. Figuring out these details in advance is crucial for the best results.

Don’t neglect your diabetes. The focus on cancer treatment can cause women to stop taking their diabetes medications as prescribed. But tightly controlling blood glucose levels before, during and after cancer treatment can make a difference in your outcome. “If your blood glucose is not well controlled and you require surgery, it is very important to get your diabetes under good control prior to surgery to aid in healing and prevention of infections,” says Dr. Halprin.

Tend to your mental health.  “Keep in mind that anything that causes stress or alters your emotional state is liable to negatively impact your blood glucoses, usually by raising them, but sometimes lowering them, and generally widely fluctuating blood glucose levels worsen emotional stress as well,” she says.

Because of the tremendous stress that often accompanies diabetes and breast cancer treatment, it’s important to seek out the support of a mental health provider, family member or friend to deal with the psychological stress of juggling these diseases.

Talk to a dietitian. Adopting a healthy diet is always beneficial, whether or not you have diabetes or breast cancer, says Dr. Halprin. But because cancer patients need a strong immune system to fight off complications during and after cancer treatment, good nutrition is especially important. A dietitian will create a personal eating plan to keep blood glucose levels normal during cancer treatment.

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  1. As a person with type 1 diabetes, my significant difficulty with chemotherapy was the accompanying steroids.
    They caused extreme havoc with my blood sugars.

  2. Thank you for writing about this topic. In 2015, within a 10 day period I was diagnosed with breast cancer and with diabetes. The diabetes had to be controlled immediately to ensure best healing after mastectomy surgery. I support all those women who have to deal with these two health issues simultaneously. Your advice to work closely with your health care team is excellent.

  3. Is there a support group for those with diabetes (type 1) and breast cancer? If so, how can I learn more about it?

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