Controlling Diabetes and Cancer Risks

Metformin may lower risks for various solid tumors and cancer deaths

/ Author:  / Reviewed by: Robert Carlson, M.D Beth Bolt, RPh

(RxWiki News) A great deal of research has been focused on cancer risks among people living with diabetes. Recent studies examined the impact that a certain diabetes medicine may have on the cancer risks of diabetes patients.

The medication metformin is widely used to manage blood sugar levels in people with type 2 diabetes.

In a systematic review of studies, Italian researchers found that metformin may reduce both the risks of a number of types of cancers and the chances of people with diabetes dying from cancer.

The authors of this review called for more randomized trials to study this association and verify or refute potential links between this therapy and cancer risks.

"Keep your blood sugar under control if you have type 2 diabetes."

Monica Franciosi, a researcher at Consorzio Mario Negri Sud in Chieti, Italy, was the lead investigator.

Studies have consistently described a link between diabetes and risks of colorectal, pancreatic and breast cancer. And increased risks of liver, gastric and endometrial malignancies have also been suggested, the authors noted.

For this study, researchers systematically reviewed available evidence on the association between exposure to metformin and the risk of various types of cancer and cancer mortality (death) in people with type 2 diabetes.

The research team combed through decades (1966-2012) of MEDLINE and EMBASE research databases to identify and analyze the results of both randomized trials, which randomly assigns groups to different therapies, and observational studies, which look at trends over time.

Among 25,307 studies identified, the investigators examined 12 randomized controlled trials involving 21,595 people living with diabetes and 41 observational studies with 1,029,389 diabetes patients.

This review looked at the association between metformin use and risks of 1) all malignancies (cancer tumors); 2) cancer death; and 3) specific cancers among people with type 2 diabetes.

Data from the observational studies showed that people with type 2 diabetes who were exposed to metformin had:

  • 27 percent lower risk of developing any type of cancer
  • 66 percent decreased risk of being diagnosed with liver cancer
  • 17 percent decline in the risk of both colorectal and stomach (gastric) cancer
  • 44 percent decreased risk of pancreatic cancer
  • 10 percent lower risk of esophageal cancer
  • 35 percent decreased risk of dying from cancer

The randomized trials did not find a significant difference in cancer risks among diabetes patients taking metformin.

“Results suggest that Metformin might be associated with a significant reduction in the risk of cancer and cancer-related mortality. Randomized trials specifically designed to evaluate the efficacy of metformin as an anticancer agent are warranted,” the authors wrote.

This study was published in August 2 in PLOS ONE.

No information on funding or conflicts of interest was provided.

Review Date: 
August 27, 2013
Last Updated:
August 28, 2013