(HealthDay News) — For patients with diabetes in the United States, metformin use is associated with a reduced risk for developing colorectal cancer, according to a study published in Cancer.

Amikar Sehdev, MD, MPH, from the University of Chicago, and colleagues examined the effects of metformin on CRC incidence in a U.S. population. Patients with diabetes and colorectal cancer were identified from MarketScan databases. 

Each case was matched for age, sex and geographical region with up to two controls; the mean age of study participants was 57 years for cases and 55 years for controls (P=1.0). In each group, about 60% of participants were men and 40% were women. Prescription tracking within the 12-month period before the index date was used to assess metformin exposure.

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The researchers found that any metformin use correlated with a 15% reduction in the odds of colorectal cancer in the multivariable model (adjusted odds ratio [OR]=0.85; 95% CI, 0.76-0.95; P=.007). The beneficial effect of metformin use was reduced to 12% after adjustment for health care use (adjusted OR=0.88; 95% CI, 0.77-1.00; P=.05). 

There was no significant association with metformin dose, duration or total exposure in dose-response analyses.

“Metformin use appears to be associated with a reduced risk of developing [colorectal cancer] among diabetic patients in the United States,” the researchers wrote.


  1. Sehdev A et al. Cancer. 2015;doi:10.1002/cncr.29165.