Elevated blood sugar levels can increase the risk of developing cancer of the colon or rectum in older women, a new study finds. 

Researchers at Albert Einstein College of medicine of Yeshiva University analyzed 12 years of data collected from 5,000 postmenopausal women in the U.S. Women’s Health Initiative study. The women’s glucose and insulin levels were measured in the beginning of the study, and then several more times over a period of 12 years. 

Eighty-one women had developed colorectal cancer by the end of the study. 

The results show that women with higher glucose levels in the beginning of the study were at a greater risk for colorectal cancer.  Women who were in the top 30 percent in glucose levels were nearly twice as likely to develop colorectal cancer as women who were in the lowest 30 percent in glucose levels. 

"The next challenge is to find the mechanism by which chronically elevated blood glucose levels may lead to colorectal cancer," said Geoffrey Kabat, Ph.D., a senior epidemiologist at Einstein and lead author of the paper. "It's possible that elevated glucose levels are linked to increased blood levels of growth factors and inflammatory factors that spur the growth of intestinal polyps, some of which later develop into cancer."

Obesity, which usually pairs with elevated blood levels of insulin and glucose, is a known risk factor for colorectal cancer, and scientists have hypothesized the development of colorectal cancer to be associated with elevated of levels of insulin. 

However, contrary to what researchers had initially thought, the results show elevated glucose, not insulin levels to be the culprit for colorectal cancer.   

Colorectal cancer is the third most commonly diagnosed cancer, and a leading cause of death in both men and women, according to the American Cancer Society.  The National Cancer Institute predicts that about 141,000 Americans will be diagnosed with colorectal cancer and 49,000 will die of it.