Diabetes Health Center

High Blood Sugar Raises Cancer Risk

Jan. 11, 2004 -- A study involving more than a million people offers some of the best evidence of an association between diabetes and an increased risk of cancer.

Researchers have found having elevated fasting blood sugar levels increased the risk of dying from cancers of the pancreas and liver, and several other malignancies.

Obesity has been associated with many negative effects on health, including some types of cancer. Because investigators took into account obesity, which is the biggest risk factor for type 2 diabetes, the findings indicate that having diabetes or being at risk for it is an independent risk factor for developing cancers.

The study was conducted in Korea, which has a much lower incidence of obesity and type 2 diabetes than the U.S. Only about a quarter of the population is overweight or obese, compared with more than half of Americans.

The research is reported in the Jan. 12 issue of the Journal of the American Medical Association.

"What this means is that the public health implications of this finding would be much greater for the United States than for Korea," study author Jonathan Samet, MD, tells WebMD. "Certainly, obesity drives blood sugar and obesity is a known risk factor for certain cancers. So this could be one of the ways in which obesity increases this risk."

1 in 31 Cancer Deaths

Approximately 150 million people worldwide have diabetes, but that number is expected to double within the next two decades as the population ages and becomes more obese and less active. While the association between diabetes and heart disease is well established, the role of diabetes in cancer has been less well understood.

In this study, researchers examined the relationship between fasting blood sugar levels and diabetes and the risk of specific cancers in just under 1.3 million Koreans enrolled in a government-run health insurance plan. During 10 years of follow-up, there were 20,566 cancer deaths among the men in the study and 5,907 cancer deaths among women.

After controlling for known cancer risk factors such as smoking and alcohol use, researchers found that the men in the study with the highest fasting blood sugar levels (those greater than 140 mg/dl) were 29% more likely to die of cancer than men with the lowest levels (those less than 90 mg/dl). The difference among women with the highest and lowest blood sugar levels was 23%.

The association was strongest for pancreatic cancer, with high blood sugar and diabetes (defined as a fasting blood sugar greater than 125mg/dl) almost doubling the risk for men and more than doubling the risk for women. An increased risk with high blood sugar or diabetes was also found for colorectal cancer and cancers of the esophagus and liver in men, and cancers of the liver and cervix in women.

The researchers estimated that 848 of the 26,473 total cancer deaths reported during the 10-year period could be attributed to diabetes and high blood sugar levels.