A study published in the
Journal of the National Cancer Institute found that men who were on their way to getting diabetes were also likely to be on their way to getting colon cancer.
Specifically, researchers tested blood samples from approximately 15,000 male doctors for C-peptide, a protein that indicates insulin levels. They found that men with the highest C-peptide levels (i.e., the highest insulin levels) were almost
three times more likely to develop colon cancer than men with the lowest C-peptide levels.
Having elevated insulin levels on a regular basis is referred to as pre-diabetes. Being overweight, somewhat sedentary, and following a Western diet are all known to contribute to the development of diabetes. And, according to this study, to colon cancer as well.
Related Research:
Source: Ma, J. and Giovannucci, E. "A Prospective Study of Plasma C-Peptide and Colorectal Cancer Risk in Men." Journal of the National Cancer Institute 96.7 (Apr. 2004): 546-553.