High Blood Sugar Raises Pancreatic, Liver, & Colorectal Cancer Risk

While most people know that high blood sugar levels are a precursor for diabetes, several studies have also suggested a link between high blood sugar levels and the risk of developing some forms of cancer.

The largest of these studies was published in the Journal of the American Medical Association in January 2005. The researchers used data from the Korean Cancer Prevention Study (KCPS) which involved more than 1.2 million Koreans between the ages of 30 and 95.

During the ten year study period, a total of 26,473 cancer deaths were recorded. The researchers found that death rates from cancer were 29 and 23 percent higher for men and women respectively for those in the highest group for fasting blood glucose (>140mg/dL) compared to those with the lowest fasting glucose levels (< 90mg/dL).

A fasting glucose level of less than 100 mg/dL is classified as normal. Those with fasting glucose levels greater than 125 mg/dL are considered to have diabetes while individuals with a level between 100mg/dL and 125mg/dL are considered to have impaired glucose tolerance, a condition also known as pre-diabetes.

In the Korean study, pancreatic cancer was found to have the strongest association with blood sugar levels. Women in the highest blood sugar group had more than twice the risk of developing pancreatic cancer compared to those in the lowest group while men in the highest group had a 91 percent increased risk of pancreatic cancer.

Other cancers that showed a correlation with blood sugar levels in men were esophageal, liver, colorectal, and bile duct cancers. The graph below shows the risk of selected cancers for the Korean men in the study, grouped by fasting glucose levels.

Graph of cancer risk in men grouped by fasting glucose levels

In women, cancers of the pancreas, liver, lung, and cervix were correlated with blood sugar levels. The risk of selected cancers in Korean women, grouped by fasting glucose levels are presented in the graph below.

Graph of cancer risk in women grouped by fasting glucose levels

The researchers estimated that as many as 3 percent of all cancer deaths in the study were attributable to having fasting blood glucose levels greater than 90 mg/dl.

A second study, consisting of 64,500 Swedish women yielded similar results. That study linked elevated fasting blood sugar levels with an increased incidence of cancers of the pancreas, skin, womb, and urinary tract. In younger women aged under 49 years there was also a link between breast cancer and high blood sugar levels. In total, women in the highest quartile of fasting blood sugar levels were 26 percent more likely to develop some form of cancer compared to those in the lowest quartile of blood sugar levels.

The reasons why high blood sugar levels increase the risk of developing certain cancers are largely unknown. One possible mechanism is that higher blood sugar levels may indicate increased stress on organs such as the pancreas (which produces insulin in response to high sugar levels) and the liver (which can store glucose in the form of glycogen).

Another possibility is that, because cancer cells require more glucose than normal cells, a high blood sugar environment in the body may increase cancerous cell growth and division. Studies have also shown that cancer cells deprived of sufficient glucose levels self destruct through a process called apoptosis.

There are numerous ways for an individual to reduce their blood sugar levels, some of these include: consuming a high fiber diet, consuming fresh, unprocessed foods, limiting sugary foods and beverages, consuming foods with a low glycemic index or glycemic load, and exercising regularly for at least 30 minutes a day, three times a week.