Recent population studies provide clues that the use of metformin may be associated with
reduced incidence and improved prognosis of certain cancers. This drug is widely used in
the treatment of type 2 diabetes, where it is often referred to as an “insulin sensitizer”
because it not only lowers blood glucose but also reduces the hyperinsulinemia associated
with insulin resistance. As insulin and insulin-like growth factors stimulate proliferation of
many normal and transformed cell types, agents that facilitate signaling through these …

Recent population studies of the biguanide metformin, commonly used to treat type 2
diabetes, suggest that its use may be associated with a lower risk—and improved prognosis—
of certain cancers. While metformin often is viewed as an “insulin sensitizer” because it
reduces the hyperinsulinemia associated with insulin resistance, the present in vitro studies
indicate that it acts not as an insulin sensitizer but as a growth inhibitor for epithelial cells.
The studies were intended to address the hypothesis that metformin exerts direct …