But if patients are educated about how to treat their diabetes while they battle cancer, they do a better job of controlling their blood sugar levels, the study found.
"I think it goes down to information being very powerful," said Dr. June McKoy, a senior author of the study who is an associate professor at Northwestern's Feinberg School of Medicine. "We have found that people with diabetes tend to do better with more information about their illness."
The study's results were published in a paper titled "Effects of Cancer Comorbidity on Disease Management: Making the Case for Diabetes Education" that ran in Oct. 31 in the online edition of the journal Population Health Management.
Like diabetes, cancer can be fought with a strengthened immune system, said McKoy, who is also director of geriatric oncology at Northwestern's Robert H. Lurie Comprehensive Cancer Center.
"If they're not caring for their diabetes, the cancer is also not taken care of," McKoy said. "Cancer is a frightening diagnosis. Their (patients') eyes glaze over after hearing 'cancer.' If they already have diabetes, it's the last thing they're focused on. A lot of people believe that cancer is a death sentence. It's not true anymore."
When cancer patients are taught how to fight their diabetes, ""it's like a light bulb goes off," she said. "Patients become empowered to take care of themselves. It's all about self-management. You have to take charge of it. The doctor's a guide."
Every cancer patient with diabetes should be seen by a certified diabetes educator to get information and support, McKoy said.
"Everyone involving the patient, including the educator, is part of a team. Patients do better when we work as a team. Registered nurses do most of the diabetes education and are certified by the state," she said.
McKoy also tells patients to see her once a month after they are diagnosed with cancer and to get their blood sugar checked three times each year.
"The hemoglobin A1c (blood-sugar) test is like a detective," McKoy said. "It is a way of assuring that a patient is following the course of their therapy and taking medication. It's like a fingerprint, so it shows whether patients have committed a crime … whether they're cheating on their diet and/or not taking their medication."
McKoy plans to study large data sets to assess which cancers patients with diabetes are getting and to see if they may be prevented.
Dr. Betul Hatipoglu, an endocrinologist at the