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Pre-existing diabetes increased mortality rate in patients with cancer
Patients with diabetes at the time of cancer diagnosis have a higher rate of mortality than those without diabetes, including a four times higher rate if the diabetes is treated with insulin, according to new study data.
“The results suggest that mortality of cancer patients with pre-existing diabetes is higher relative to non-diabetic patients for all cancers combined and for most individual cancer sites,” Kristina Ranc, a research assistant at the University of Copenhagen and Steno Diabetes Center, Gentofte, Denmark, said in a press release. “In general, the highest mortality was found for insulin-treated patients, suggesting that cancer patients with more intensive diabetes treatment have a larger degree of comorbidity at the time of cancer diagnosis, and hence poorer survival. Diabetes duration at cancer diagnosis did not influence the prognosis.”
Ranc and colleagues looked at national registries in Denmark from 1995 to 2009 and found 426,129 patients diagnosed with cancer. Of those, 42,205 were diagnosed with diabetes before their cancer diagnosis.
They found that no matter the treatment for diabetes — no medications (n=15,433), oral hypoglycemic agents (n=17,708) or insulin (n=9,044) — there were significant increases in mortality for all cancers combined and for colorectal, breast, ovary, bladder, cervix and corpus uteri, according to the study.
Specifically, patients with diabetes duration of longer than 2 years who were treated with insulin demonstrated the highest mortality rates when all cancers were considered. These rates were at 3.7 (95% CI, 2.7-5.1) for men and 4.4 (95% CI, 3.1-6.5) for women 1 year from cancer diagnosis and rose to 5 (95% CI, 3.5-7) for men and 6.5 (95% CI, 4.2-9.3) for women at 9 years post-cancer diagnosis.
“Our study provides strong support for the notion that pre-existing diabetes increases mortality among cancer patients, and that the excess mortality is larger among patients with diabetes treated with [oral hypoglycemic agents] or, particularly, insulin,” the researchers wrote. “It is crucial that cancer patients with diabetes receive optimal diabetes treatment as well as any cancer-specific therapy; a therapeutic challenge requiring close collaboration between oncologists and endocrinologists.”
Disclosure: Marit E. Jørgensen and Bendix Carstensen are employed by Steno Diabetes Center, a research hospital working in the Danish National Health Service and owned by Novo Nordisk A/S. BXC and MAEJ hold shares in Novo Nordisk A/S.