A Standby in Diabetes Therapy Protects against Some Cancers

Type 2 diabetes, as well as abdominal obesity and other conditions associated with insulin resistance, are associated with an increased risk of death from a range of solid tumors, including cancer of the breast, colon, and pancreas.  This led a trio of British researchers to study the risk of developing cancer over a 5-year period in diabetics taking insulin and/or metformin.  Their results have been published in the journal Diabetologia.  

The findings came from 62,000 patients of 300 British family doctors.  Patients on insulin were twice as likely as those on metformin to develop colon cancer, and 4½ times as likely to develop pancreatic cancer.  In patients on insulin alone, there was a 6-fold increase in all forms of cancer, compared with those taking metformin alone.  The rate of cancer in metformin-only treated diabetics was similar to that in diabetics treated with diet and exercise.  Metformin use failed to influence the risk of breast or prostate cancer.

A diabetic specialist from Sweden at the recent European Association for the Study of Diabetes meeting has indicated that metformin itself is an anti-cancer agent – it targets cancer stem cells that remain after chemotherapy that may cause metastases; he plans to start studies with metformin in non-diabetic patients.