Diabetes Medication Reduces Cancer Risk
December 6, 2013

Diabetes Drug Lowers Cancer Risk For Female Patients

Brett Smith for redOrbit.com - Your Universe Online

A study led by researchers at the Cleveland Clinic has found a certain class of oral medications used to treat type 2 diabetes reduces the risk of female patients also developing cancer.

Cancer is more common in patients with diabetes than in those without the condition and women with diabetes appear to be at a high risk of breast cancer and cancers of the reproductive tract. Many cancer cells have also been found to have receptors for insulin, which acts as a growth factor.

The lowered risk of cancer was only seen in female patients with type 2 diabetes and was most pronounced in women taking insulin sensitizer drugs called thiazolidinediones, or TZDs.

In the study, which was published by the journal Diabetes, Obesity and Metabolism, researchers examined the electronic health record-based Cleveland Clinic Diabetes Registry, which includes nearly 26,000 patients. The researchers also looked at the histology-based tumor registry, which included over 48,000 cases of cancer from 1998 to 2006. Over 890 cancer cases were identified between the two databases.

The researchers also looked at the effects of two different diabetes drugs – insulin sensitizers and insulin secretagogues. Insulin sensitizers work on the body by increasing various tissues’ response to insulin. Insulin secretagogues stimulate pancreatic beta cells to make more insulin.

The study team found female patients with type 2 diabetes who took insulin sensitizers showed a 21 percent cancer risk compared with those who took insulin secretagogues. They also found that a specific group of sensitizers, called thiazolidinediones, was associated with a 32 percent lower cancer risk in female patients compared with sulphonylurea, an insulin secretagogue. Results showed no significant difference in men.

"What this study shows us is that using insulin secretagogues to increase insulin production correlates with an increased cancer risk in women with type 2 diabetes," said study author Dr. Sangeeta Kashyap, an endocrinologist and associate professor of medicine at Cleveland Clinic. "By contrast, insulin sensitizers cut insulin levels and can decrease cancer growth. So, clearly, when prescribing anti-diabetic medications, it's important to consider the impact a drug has on fueling cancer growth."

The researchers said they weren’t sure why men with type 2 diabetes didn’t see the same benefit from insulin sensitizers as their female counterparts, but speculated sex hormones may play a role.

The new study comes just as the Food and Drug Administration is lifting most restrictions on the use of the drug Avandia, an insulin sensitizer. After a Cleveland Clinic cardiologist, Dr. Steven Nissen, published a study suggesting Avandia increased the risk of heart attack or stroke, the FDA temporarily clamped down on its use.

Insulin sensitizers are also widely available as cheap generic drugs. Kashyap told the Los Angeles Times the additional value of insulin sensitizers should encourage endocrinologists to think more broadly about their patients' risks when prescribing a medication.

“This is good news," he said. "This tells us doctors when we’re treating people for diabetes that we need to think not just about their heart disease risk or the possibility of weight gain, but about cancer too.”