For individuals with Type 1 diabetes, maintaining healthy blood sugar levels could be not only a necessity for long-term health, but also the key to staying mentally sharp. A study published in the online version of the journal “Diabetes” states that increased exposure to hyperglycemia — elevated levels of blood sugar — is associated with negative effects on brain size, including a decrease in whole brain gray matter. Meanwhile, hypoglycemia is associated with more severe decreases in occipital/parietal white matter volume.
The study was headed by Dana C. Perantie of the Washington University School of Medicine, located in St. Louis, Missouri. Dr. Perantie’s team analyzed physiological changes in brain regions in youths who had Type 1 diabetes when they were exposed to blood sugar levels on both the high and low ends of the spectrum. The control group for the study was comprised of the children’s siblings, who did not have Type 1 diabetes.
At baseline — the beginning of the study — each of the participants underwent brain neuroimaging. Doctors followed up with patients for two years, and patients underwent neuroimaging once again at the end of the follow-up period. Throughout the follow-up, a variety of glucose control measurements were recorded, including HbA1c levels, results from glucose meter readings, and self-reported episodes of severe hypoglycemia. After the neuroimaging was complete at the end of the follow-up, researchers studied whole brain and voxel-wise changes in the volume of gray and white matter in the study participants. Results were also adjusted for age, gender, and the age at which the patients were diagnosed with diabetes.
The findings showed no differences between patients with Type 1 diabetes and the control group in whole brain and voxel-wise brain volume throughout the two-year follow up. However, the patients in the group with Type 1 diabetes who had more hyperglycemia showed a significant decrease in whole gray brain matter than those who had less hyperglycemia. In addition, patients with Type 1 diabetes who experienced severe hypoglycemia showed significant decreases occipital/parietal white matter volume over both the control group and the group of Type 1 diabetics who had not experienced severe hypoglycemia.
“Within diabetes, exposure to hyperglycemia and severe hypoglycemia may result in subtle deviation from normal developmental trajectories of the brain,” commented the authors of the study.
The subject of changes in brain physiology related to Type 1 diabetes has been previously studied in previous research. A 2007 study published in the journal “Diabetes Care” used magnetic resonance imaging (MRIs) to study differences in brain volume among children with Type 1 diabetes and their non-diabetic siblings, age 7 to 17. The study similarly found that volume of grey and white brain matter did not differ significantly between diabetics and non-diabetics, but patients who had a history of severe hypoglycemia displayed reduced gray matter volume in the left superior temporal region. Additionally, patients who had a history of hyperglycemia showed smaller white matter volume in the right posterior parietal region and larger gray matter volume in the right prefrontal region.
The authors concluded that “qualitatively different relationships were found between hypo- and hyperglycemia and regional brain volumes in youth with type 1 diabetes.” They also commented that future research would be necessary to determine what effect, if any, the changes in brain volume would have on cognitive function and whether further exposure to extreme blood sugar conditions would have additional effects on brain matter volume.