Abstract
The incidence of diabetes is markedly increasing worldwide. In addition to cardiovascular complications, many epidemiological studies have demonstrated that diabetic patients have a markedly increased risk of developing many types of cancer and several meta-analyses have found that metformin, the most commonly prescribed medication for type 2 diabetes, is associated with a lower risk of developing several cancers. Therefore, the suggested mechanism of metformin in the reduction of breast cancer will be discussed in this review.