Higher Blood Sugar May Mean Lower Risk of Brain Cancer

Many cancers, such as colon, breast and bladder, are more common among patients who have elevated blood sugar and diabetes. However, recent research finds the opposite relationship when it comes to brain tumors. Gliomas, cancerous brain tumors, are less common among patients with elevated blood sugar and diabetes, according to the study published in Scientific Reports.

Glioma is one of the most common types of cancerous tumors, which originates in the brain. It is typically diagnosed at middle age, and although there are treatments in development, no current therapy ensures long-term survival.

Lead researcher Judith Schwartzbaum, Ph.D., said in a statement, “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.”

Schwartzbaum, associate professor of epidemiology and researcher at The Ohio State Comprehensive Cancer Center, has led previous research studies which found that high blood sugar appears to reduce a person’s risk of meningioma, a non-cancerous brain tumor.

Schwartzbaum went on to comment that the inverse relationship “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.”

As the authors write in the study, “elevated consumption of blood glucose by the preclinical tumor may account for the apparent reduction of glioma risk among people with diabetes or elevated blood glucose level.” They go on to cite a phenomenon called the Warburg effect: that cancer cells, in general, consume more glucose than non-proliferating cells. If this effect were present, the authors explain, the inverse association between the tumor and blood sugar levels would be the strongest near the time of the glioma diagnosis.

This study combined data from two large, long-term studies. The Apolipoprotein Mortality RISk (AMORIS) study included 528,580 Swedish patients, while the Metabolic syndrome and Cancer project (Me-Can) study included 269,365 patients from Austria and Sweden. Overall, a total of 812 patients developed gliomas.

The researchers evaluated the data on blood sugar and diabetes, and its relationship to the subsequent development of brain cancer. Those with elevated blood sugar and diabetes were found to have a lower risk of developing glioma. This relationship was the strongest within a year of cancer diagnosis.

Overall, the authors stated that, while their findings further support the inverse association between blood sugar and glioma, evidence for the presence of the Warburg effect as the cause of this relationship was mixed. Data from the AMORIS study supported this effect, but data from the Me-Can study did not.

There have been mixed results in other studies evaluating restrictive diets and their effect on brain cancer development. More research is needed to determine whether there is some way to modify the sugar/tumor relationship that will benefit patients with brain cancer.