Whereas obesity and related conditions such as diabetes and Metabolic Syndrome have been linked with colorectal cancer, previous research has not ascertained whether the risk relates to levels of circulating insulin (role as an anti-apoptotic and mitogenic agent) or glucose (potential energy source for malignant cells).  Geoffrey C. Kabat, from the Albert Einstein College of Medicine (New York, USA), and colleagues analyzed data from a 4,902 women participating in the Women's Health Initiative who had baseline and serial follow-up measurements of fasting serum glucose and insulin. The team also tracked subjects’ age, body mass index (BMI), alcohol consumption, physical activity, ethnicity, and family history of colorectal cancer. During a median of 11.9 years, there were 81 cases of colorectal cancer :  65 of the cases were colon cancer, in six the malignancy was the rectosigmoid junction, and in 10 the cancer was rectal. As compared with women who did not develop colorectal cancer, those who did were older by about two years, and less likely to be physically active. The researchers observed that while glucose displayed a "robust" association, baseline levels of insulin and the insulin resistance index were not associated with an increased risk of colorectal or colon cancer.   The risk for both colorectal and colon cancer with higher levels of glucose was seen in patients whose BMI was 27.76 or higher.  The study authors conclude that: “These data suggest that elevated serum glucose levels may be a risk factor for colorectal cancer in postmenopausal women.”