Metformin and basal cell carcinoma: what the research found

A 2021 case-control study from Iceland examined nearly 7,000 people with a diagnosis of skin cancer (basal cell carcinoma or squamous cell carcinoma) and nearly 70,000 others. The authors discovered that:

• People taking metformin, even at very low doses, were about 30% less likely to develop basal cell carcinoma.
• There was no effect on the frequency of squamous cell carcinoma, but those who developed squamous cell carcinoma were likelier to have the less serious in situ type.

This observational association does not prove that metformin prevented cancer. Do not start or change diabetes medication for skin cancer prevention on the basis of this study. The study did not specifically examine whether metformin can be used effectively in people with a history of multiple basal cell carcinomas to prevent future BCCs from occurring, and they suggest that further studies should examine this.

Reference

Adalsteinsson J, Muzumdar S, Waldman R et al,  2021.  Metformin is associated with decreased risk of basal cell carcinoma: A whole-population case-control study from Iceland. Journal of the American Academy of Dermatology, volume 85, issue 1, pages 56-61, 1 July 2021.