It is no secret that the incidence of cancer and diabetes as single diseases continue to increase but is there an association between diabetes and cancer? Diabetes and Cancer are disruptions in the body's normal metabolism. These two chronic conditions share risk factors including age, sex, obesity, physical inactivity, unhealthy diet, alcohol and smoking. Obesity, the most important risk factor for diabetes is now recognized as a risk factor for several cancers. Some of these risk factors can be modified and managed with improvement in self-care. Please, don’t misunderstand, there are several other causes of both of these chronic conditions such as genetics and heredity. Diabetes and cancer share similar symptom profiles such as fatigue, pain, numbness/tingling and decreased kidney function. Publications on the connection between cancer and diabetes give us convincing evidence that diabetes (mainly Type 2) does increase the risk for several cancers such as breast, colorectal, pancreas, and liver. The experts tell us that diabetes is associated with premature death from some cancers (i.e. pancreas, lung), have a poorer prognosis and are at increased risk of complications during cancer treatments. If we know we are at an increased risk, then we have to ask ourselves why. This a topic deserving a lot of research and reasons aren’t clearly defined at this time. It could have something to do with high insulin levels, high blood glucose levels and the inflammation in cells. Over the years there have been reports that some of the diabetes medications we use to treat our condition could cause different cancers and this continues to be an ongoing area of research.
Management of diabetes in patients with cancer
The side effects of cancer therapies vary among patients. Some of the more common side effects could include: nausea, vomiting, loss of appetite, sore mouth, fever, infection and numbness in fingers/toes (not all inclusive). Not all drugs have the same degree of nausea or other side effects so be sure not to assume anything about your treatment unless you have discussed it with your Cancer Care Team. What happened in one person may not happen to you at all. I have practised in the area of cancer for years and many times people say they knew someone who had terrible nausea but maybe that person’s medication was at the high end of the nausea scale and your medication could be at the lower end. Likewise, hair loss does not occur with all cancer treatments.
How can cancer affect my diabetes management?
1)Changes in eating patterns- which could result if nausea/vomiting occurs, loss of appetite occurs, taste of food is lost or you have a sore mouth and difficulty in swallowing. Any one of these could increase the risk of low blood sugar levels (hypoglycemia). Pay attention to your sick day guidelines (https://www.diabetes.ca). If you don’t already have a scale to adjust insulin, ask your health care team to provide one for you. Having this insulin scale will allow you to either add or subtract insulin from your normal dose based on the sugar readings. For Type 2 patients who take oral medications, ask which drug(s) you might be able to omit or reduce the dose of if repeated episodes of low blood sugar happen.
2)Treatment medications or fluids- very few cancer drugs cause a rise in blood sugar, but sometimes the problem is the fluid used to give the medication. A drug commonly used to treat or prevent nausea could raise blood sugars. When you receive your counselling, be sure your team knows you have diabetes and ask for guidance on what you can do if sugars are high. A similar type of insulin scale can be used for high blood sugars just like low blood sugars mentioned in #1.
3)Lack of activity could increase blood glucose values since you have little energy and your quality of life is poor such as having a hard time to breathe on exertion. Hyperglycemia could delay or affect the response to cancer treatment. Cancer can certainly be stressful so that too could rise blood sugars. Never hesitate to ask for a consultation to a social worker or psychologist to help you deal with the stress and worries of having cancer.
4)Surgery for cancer might include fasting (not eating for hours) leading to the risk of hypoglycemia. There is an abundance of evidence telling us that good sugar control improves surgical outcomes so getting the diabetes in control post surgery is important. If you are unable to swallow your oral medications then the doctor may prescribe the short-term use of insulin.
5)Chronic diseases- such as heart disease, poor kidney function, numbness or loss of sensation in your fingers/toes could worsen with cancer treatments. If kidney function is diminished, then drugs do not get removed from your body as fast. The drug(s) may accumulate and last longer in your system. This might increase the risk or severity of side effects. The Cancer Care Team does monitor all of this information. Knowing how well your kidney functions is extremely important since many patients with diabetes already have this as a complication of their disease. Some cancer drugs may affect the heart function. By now you can understand why your specialist puts you through so many tests before a cancer diagnosis is confirmed. The Cancer Care Team must have a good understanding of how your body functions, so do not keep any secrets.
What could happen if I don’t manage my diabetes while getting cancer treatment since the cancer is the prime focus for me right now?
Once the diagnosis of cancer is made many cancer patients may let their diabetes take a backseat to their cancer therapy. Some cancer management involves taking medications by mouth and many patients will say “oh no, more pills. I get so discouraged” that they may let their other diseases suffer. In a study published in 2016 by X.Tan et al., the study assessed oral antidiabetic drug use and associated it with health outcomes in non-elderly adults with cancer. Of 1918 diabetic cancer patients who were newly started on oral antidiabetic drugs, approximately 35% were non- compliant to the new diabetic medication. However, those who did comply to the oral diabetes drugs, had 24% less all-cause hospitalizations (reference below).
If blood glucose remains elevated over extended periods of time the following could happen;
(1) An increase in the risk of infections- the body’s ability to fight infection is weakened when sugars are consistently over 11mmol/L (200mg/dL). Developing a fever in a patient with cancer is a very serious complication. You may have to be admitted to the hospital for more investigations and antibiotic treatment(s). Decrease your risk of infections with good blood sugar control, good hand washing, avoiding close contact with people that have a cold or flu and avoid crowded spaces where germs could be spread very easily. Remember to check with your speciality team about vaccinations against the flu, pneumonia and shingles.
(2) Increase thirst/or dehydration- high blood glucose can make you thirsty so drinking more fluid is important to avoid dehydration (fluid is lost without it being replaced). You will urinate more often but that is ok as long as you are able and stable to walk and go to the bathroom. You don’t want to risk a fall and if this is a risk then consider the purchase of a walker. Remember to speak to a specialist on walker choice (pharmacist, home health care centers, physiotherapist, etc). You may even have insurance that would contribute to the cost. If you become dehydrated from diarrhea, vomiting or poor eating then different body functions can be impaired and this could interfere with your planned chemotherapy treatment or result in a lower dose being ordered.
(3) Increased fatigue/tiredness/pain severity- these symptoms can occur due to the cancer but can be elevated when diabetes with high blood sugars occur over a period of time.
I will stop at this point as I could go on forever. I hope I have informed you on the importance of diabetes management during cancer therapies. It can make a difference on your well-being short and long-term. I can’t promise that it will be easy and I understand that it is one more thing to do so all health providers ask is that you do your best. Never feel ashamed to ask for help or guidance, no matter what the situation. There are services to help and guide you.
My final tips:
· Ask for help if/when needed
· Do your best to keep your blood sugars in decent control. Set a goal with your diabetes team which is reasonable, it doesn’t have to be perfect
· Consult your cancer care team for side effect management from your chemo. You do not have to suffer from prolonged nausea or vomiting as many newer and effective medications are on the market
· Talk with your family/close friends about what they can do to help. Be sure they know how to treat a low blood sugar reaction in case you are unable to recognize the symptoms or access treatment in your home
· It might be a good idea to take a snack with you during your chemo treatment. Clinics usually have snacks but it may not be what you feel like eating or you know it will raise your blood sugar too much
· There is a new treatment on the market which is intranasal glucagon for treatment of low blood sugar reactions. You might have had to use the injectable glucagon previously so this offers the advantage of it being used like a nasal spray. It is available with or without a prescription but with a prescription your insurance might cover it. It is wise to check before purchasing. Ask your diabetes care team more about this product
· Financial toxicity- if your diabetes or cancer therapy is not paid by your insurance plan or you have no medicine coverage, do check with either your Diabetes Team or Cancer Team to see how they may be able to help. Many drug manufacturers provide a compassionate supply of medication when someone qualifies.
My wish for anyone reading today’s blog is that no one has to suffer this combination of diseases or either alone but I know that is not a practical wish so all I can ask is that you and your care family learn all they can to make this part of life’s journey a bit easier for you. Do take care.
Please refer to the Canadian Cancer Society or Diabetes Canada websites for more tips on improving disease control. The daffodil is a symbol used by the Canadian Cancer Society in April to raise funds for cancer research. References:
1)The global implications of diabetes and cancer- www.thelancet.com accessed online April 21, 2020
2)Diabetes and Cancer, A consensus report: Diabetes Care, 2010
3)An International Journal of Medicine 2012: 105:3-9
4)X.Tan et al. Oral antidiabetic drug use and associated health outcomes in cancer patients. Journal of Pharmacy and Therapeutics, 2016, 41, 524-531
5)Hershey,DS et al. Hyperglycemic-Inducing NeoAdjuvant Agents Used in Treatment of Solid Tumors: A Review of the Literature . Oncology Nursing Forum, 2014, 41, E343-E354
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