Glioma Risk Lower with Elevated Blood Sugar

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.

Glioma is a heterogeneous primary brain tumor for which there is no treatment that ensures long-term survival and patients diagnosed with the most common adult form of this tumor, glioblastoma, survive on average only 14 months.

An international team of scientists led by those at the Ohio State University 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. They used data from the Apolipoprotein MOrtality RISk (AMORIS) (n = 528,580) and the Metabolic syndrome and Cancer project (Me-Can) cohorts (n = 269,365). They identified individuals who were followed for a maximum of 15 years after their first blood glucose test until glioma diagnosis, death, emigration or the end of follow-up.

They conducted an exploratory analysis of the 51 glioma cases using the Me-Can data set with multiple measurements to determine whether glucose values equal to or less than 7.0 mmol/L varied with the number of measurements or time between the blood glucose test and glioma diagnosis. They found that fasting and non-fasting glucose dose-response relationships were similar allowing them to combine data from these two groups.

They found that the relative proportions of male and female total glioma cases differ between the cohorts (in AMORIS 65% are men; in Me-Can 52%), as does fasting status (in AMORIS 61% of blood was drawn when total glioma cases were fasting; in Me-Can all blood samples were collected from fasting participants). Pre-diagnostic blood glucose levels were inversely related to glioma risk and pre-diagnostic diabetes. During the year before diagnosis, blood glucose was inversely associated with glioma in the AMORIS but not the Me-Can cohort. This AMORIS result is consistent with their hypothesis that excess glucose consumption by the preclinical tumor accounts for the inverse association between blood glucose and glioma.

Judith Schwartzbaum, PhD, a professor and lead author of the study said, “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.” The study was published on May 3, 2017, in the journal Scientific Reports.