The Counterintuitive Relationship between Diabetes and Brain Cancer

According to the modern medical science, there is growing evidence for the positive association between hyperglycemia and malignant cancer development (among other conditions). This is particularly true for diabetes type 2 patients, which are at greater risk of developing pancreatic, liver, colorectal, endometrial and some other cancers. Although this association is well-documented, and the Warburg effect might be involved, its exact mechanisms remain poorly understood.

To complicate things further, research at the Ohio State University has recently uncovered an opposite relationship with brain cancer: hyperglycemia/diabetes is negatively associated with brain cancer. This line of research is being led by epidemiology specialist Judith Schwartzbaum, who lectures at the Ohio State University.

Unexpected discovery

The counterintuitive insight that high blood sugar is negatively associated with brain tumors began with the discovery of a lower incidence of meningioma among diabetic people. In this first study — published in the British Journal of Cancer in 2016 — Judith Schwartzbaum and her colleagues analyzed blood tests from more than 40,000 people from Sweden, and found lower rates of meningioma among those with high blood sugar.

This link was found to be especially strong in women, the sex most affected by this type of brain tumor. Women with the lowest blood sugar readings were at least two times more likely to develop meningioma than those with the highest blood sugar levels. Researchers suspect that the key to understand how these brain tumors develop may lie in hormones.

More recently, the same research team uncovered a similar association with glioma, the most common malignant brain tumor. This discovery also resulted from the analysis of a large amount of clinical data collected from hundreds of thousands of Swedish and Austrian people. Schwartzbaum and her team found that blood sugar levels among the 812 participants who developed gliomas were less likely to stray on the upper end. Schwartzbaum hypothesizes that high blood sugar may protect the brain against tumors, or that brain tumors somehow lower blood sugar levels.

Promising insights to be found

There is currently no explanation for these bizarre discoveries, and they’re even more surprising given that the brain itself consumes 20% of the body’s energy fuel – glucose. Researchers anticipate that these new findings could help understand how other brain cancers develop. They are also a potentially excellent opportunity to develop new therapeutic methods to treat brain cancers. More research is necessary to understand whether the link between hypergycemia and brain cancer is causal or incidental.