New research further illuminates the surprising relationship between blood sugar and brain tumors and could begin to shed light on how certain cancers develop.
While many cancers are more common among those with diabetes, cancerous brain tumors called gliomas are less common among those with elevated blood sugar and diabetes, a study in the journal Scientific Reports has found.
The discovery builds on previous research showing that high blood sugar appears to reduce a person's risk of a noncancerous brain tumor called meningioma. "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," said the senior author.
Glioma is one of the most common types of cancerous tumors originating in the brain. It begins in the cells that surround nerve cells and help them function. The disease is typically diagnosed in middle age. At present, there is no treatment that ensures long-term survival, but several potential options are being studied.
The Scientific Reports paper included data from two large long-term studies. One, called AMORIS, included 528,580 Swedes. The second, Me-Can, consisted of 269,365 Austrians and Swedes. In all, 812 participants developed gliomas.
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.
"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?" senior author said.
The researchers found that this relationship was strongest within a year of cancer diagnosis.
"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," senior author said.
"For example, insulin-like growth factor is associated with glioma recurrence and is found in lower levels in people with diabetes than those who don't have the disease."
The brain accounts for only about 2 percent of body weight, but consumes about 20 percent of the body's available glucose, senior author said.
The body of research on restrictive diets and their effect on brain cancer development has shown mixed results and more work is needed to determine if there's something about the sugar/tumor relationship that can be modified in a way that's beneficial to brain cancer patients, senior author said.
Surprising link between blood sugar and brain cancer found
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