Diabetes has been associated with advanced stages of cancer and increased mortality in patients with breast cancer. However, diabetes is often undiagnosed until after the breast cancer diagnosis, according to a recently published study in BMC Cancer.

“Our objectives were to identify factors associated with previously undiagnosed diabetes in breast cancer, and to examine associations between previously undiagnosed diabetes and cancer stage, treatment patterns, and mortality,” the authors wrote in the study.

The researchers identified 2,418 women who were diagnosed with breast cancer and diabetes between January 2001 and December 2005. Diabetes was classified as previously diagnosed if it was identified between 4 and 24 months before the cancer diagnosis and previously undiagnosed if it was identified from 3 months before to 3 months after the cancer diagnosis.

Multivariate analyses were performed to examine risk factors for previously undiagnosed diabetes and associations between undiagnosed diabetes, cancer stage, treatment, and mortality.

The researchers found that 634 (26%) of the patients included in the study had previously undiagnosed diabetes, which was associated with advanced stages of cancer and higher mortality rates.

The authors said biological factors, such as higher insulin levels due to untreated disease, underlying the association between previously diagnosed diabetes and breast cancer could differ in patients whose diabetes is not discovered until they are diagnosed with cancer.

“In breast cancer, previously undiagnosed diabetes is associated with advanced stage cancer and increased mortality,” the authors wrote. “Identifying biological factors would require further investigation.”

For more information:

Griffiths RI. BMC Cancer. 2012, 12:613. doi:10.1186/1471-2407-12-613.

Disclosures: The researchers have no relevant financial disclosures.