(HealthDay News) — For patients with diabetes in the United States, metformin use is associated with reduced risk of developing colorectal cancer (CRC), according to a study published in the April 1 issue of 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 CRC 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 male and 40% were female. Prescription tracking within the 12-month period before the index date was used to assess metformin exposure.

The researchers found that any metformin use correlated with a 15% reduction in the odds of CRC in the multivariable model (adjusted odds ratio, 0.85; 95% confidence interval, 0.76–0.95; P=0.007). The beneficial effect of metformin use was reduced to 12% after adjustment for health care use (adjusted odds ratio, 0.88; 95% confidence interval, 0.77–1.00; P=0.05). 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 CRC among diabetic patients in the United States,” the authors write.

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