"It's a big deal if we can take a cancer and knock its mortality rate down by 5 percent or 10 percent, " says Dr. Brancati.

CNN: Diabetes increases cancer mortality risk

"It's something that is hiding in plain sight, " says Brancati.

CNN: Diabetes increases cancer mortality risk

If researchers can tease out the reason why, they might have an opportunity to reduce cancer deaths by focusing on diabetes-related health problems, says lead author Frederick Brancati, M.

CNN: Diabetes increases cancer mortality risk

In the new study, Brancati and colleagues analyzed all the available research and selected 23 well-designed studies that looked at cancer patients who had diabetes at the time of diagnosis.

CNN: Diabetes increases cancer mortality risk