Elevated blood sugar is associated with colorectal cancer in postmenopausal women

Summary: women in the highest third of blood glucose levels were almost twice as likely to develop colorectal cancer over the course of the study.More evidence that high blood sugar contributes to cancer is presented in a study just published in the British Journal of Cancer that examines the link between elevated fasting glucose and colorectal cancer in postmenopausal women. The authors state:

"It is unclear whether circulating insulin or glucose levels are associated with increased risk of colorectal cancer. Few prospective studies have examined this question, and only one study had repeated measurements."

So they examined baseline fasting serum insulin and glucose values for 4902 non-diabetic women over 12 years, during which 81 cases of colorectal cancer turned up. The data showed a significant trend:

"Baseline glucose levels were positively associated with colorectal cancer and colon cancer risk: multivariable-adjusted hazard ratio (HR) comparing the highest (greater than or equal to 99.5 mg dl−1) with the lowest tertile (<89.5 mg dl−1): 1.74 and 2.25, respectively. Serum insulin and homeostasis model assessment were not associated with risk."

In other words, glucose in the highest third almost doubles the risk. In this non-diabetic group an association with fasting insulin levels was not observed. However, I can say through extensive experience over 2-3 years having patients suffer through an extended glucose + insulin tolerance test that insulin can be often elevated later in the test but not in the fasting sample. The authors conclude:

"These data suggest that elevated serum glucose levels may be a risk factor for colorectal cancer in postmenopausal women."