High blood sugar appears to reduce a person’s risk of brain tumor, study

In what they call a “surprising link,” researchers have found that cancerous brain tumors called gliomas are less common among those with elevated blood sugar and diabetes.

The new discovery, reported this week in the Scientific Reports, build on previous research findings at the Ohio State University that high blood sugar appears to reduce a person’s risk of a noncancerous brain tumor called meningioma.

As one of the most common types of cancerous tumors originating in the brain, glioma begins in the cells that surround nerve cells and help them function. While it is typically diagnosed in middle age, there is no treatment now that ensures long-term survival.

Supported by the U.S. National Cancer Institute, the research included data from two large long-term studies: one, known as AMORIS, consisted of 528,580 Swedes; the second, called Me-Can, consisted of 269,365 Austrians and Swedes. In all, 812 participants developed gliomas.

“Diabetes and elevated blood sugar increase the risk of cancer at several sites including the colon, breast and bladder. But in this case, these rare malignant brain tumors are more common among people who have normal levels of blood glucose than those with high blood sugar or diabetes,” Judith Schwartzbaum, an associate professor of epidemiology and a researcher in Ohio State’s Comprehensive Cancer Center, was quoted as saying in a news release.

The researchers evaluated blood sugar and diabetes data and its relationship to subsequent development of brain cancer and found that those with elevated blood sugar and diabetes had a lower risk of developing glioma, and that this relationship was strongest within a year of cancer diagnosis.

“This really prompts the question, ‘Why is the association between blood glucose levels and brain cancer the opposite of that for several other cancerous tumors?” Schwartzbaum said. “This may suggest that the tumor itself affects blood glucose levels or that elevated blood sugar or diabetes may paradoxically be associated with a protective factor that reduces brain tumor risk.”

The brain accounts for only about 2 percent of body weight, but consumes about 20 percent of the body’s available glucose. “Our research raises questions that, when answered, will lead to a better understanding of the mechanisms involved in glioma development,” she said.