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Intriguing Links Between Diabetes and Cancer

Network - Fall 2010

By Mary Brolley

Cancer and diabetes have a complicated relationship.

And with an estimated one in five cancer patients also facing diabetes, it’s important to try to sort this out.

Diabetes is suspected of increasing the risk of certain types of cancer.

On the other hand, certain types of cancer and cancer treatments may cause or worsen diabetes.

And metformin, a common treatment for type 2 diabetes, has been associated with a lower risk of cancer in some studies.

So it’s not surprising that researchers in endocrinology and oncology are increasingly focused on the similarities between the two conditions and what can be learned by combining their efforts.

Earlier this year, the American Diabetes Association and the American Cancer Society issued a joint paper on the two diseases, agreeing that accumulating evidence indicates that people with diabetes are more prone to certain cancers.

Diabetes seems to be present before the advent of some colorectal and prostate cancers, and people with the disease are more likely to get pancreatic cancer.

Diabetes is also linked to increased risk for breast and endometrial cancers.

There is a certain inevitability about the linking of the two diseases, says Veronica Brady, advanced practice nurse in the Diabetes Program in the Department of Endocrine Neoplasia and Hormonal Disorders at MD Anderson.

“Both diseases occur more often in older, physically inactive, overweight or obese people,” she says. “We must address it, because eventually the populations are going to cross.”

Acknowledging the connection

MD Anderson’s Diabetes Program was created to address the fact that the diseases coexist. Preliminary research at the institution showed that, among patients with diabetes and pancreatic cancer, those with higher blood sugar had worse outcomes.

Patients referred to the program receive education about diabetes and glucose monitoring, counseling on diet and exercise, and a dose of reassurance that diabetes can be managed.

“I tell them, ‘We’ll help you control your diabetes during treatment and beyond,’ ” Brady says.

Newly diagnosed cancer patients with hyperglycemia or diabetes get a lot of attention from the staff. “We know they have increased mortality just because they have a comorbidity,” she says.

“Patients can also experience steroid-induced hyperglycemia, so we need to monitor for this in patients receiving steroids,” she says.

Meanwhile, recent studies indicate that the commonly prescribed diabetes drug metformin is associated with a lower risk of certain cancers.

Could the relationship be as simple as overlapping populations? Risk factors for both diseases include advancing age, being overweight or obese, physical inactivity and smoking.

Even if this is the case, diabetes and obesity are increasing rapidly in the United States, so addressing how diabetes may be prevented or managed is a crucial topic.

Most important, Brady says, is an emphasis on the maintenance of good general health so the patient can undergo the rigors of treatment for cancer.

‘A measure of control’

As consensus mounts that the two conditions are linked, the best advice for people with diabetes facing cancer is to watch blood sugar, stay as active as possible, eat a healthful diet, take medications as prescribed and reduce stress.

And, whether they have cancer or not, all people with diabetes might be wise to discuss their risk of cancer with their physician.

Brady says that, despite undergoing rigorous cancer treatment, many of her patients are eager to become vigilant about their blood sugar.

“Some patients will really focus on this,” she says. “They exercise, watch what they eat, take their meds. It gives them a measure of control.”

© 2015 The University of Texas MD Anderson Cancer Center