According to a new longitudinal study published in Diabetes Care, a journal of the American Diabetes Association, brain volume, verbal IQ, and total IQ are lower in children with type 1 diabetes (T1D) than in children without diabetes.
In the nearly eight-year study conducted by Dr. Nelly Mauras, a clinical research scientist at Nemours Children’s Health System in Jacksonville, Florida, and Dr. Allan Reiss, a professor at Stanford University Medical School in California, brain scans of young people who have T1D were compared to those of non-diabetic children to assess the extent to which glycemic exposure adversely affects the developing brain can.
“Our results show that people with T1D are at risk of cognitive dysfunction despite the improved blood sugar control now possible with new technologies,” said Mauras, principal investigator on the study and head of the Nemours Department of Endocrinology, Diabetes and Metabolism Children’s Health System in Jacksonville, Florida and Professor of Pediatrics at Mayo College of Medicine. “Our longitudinal data support the hypothesis that the brain is a target of diabetes complications in young children. Whether these changes can be reversed with careful diabetes control needs further investigation.”
The research team at DirecNet (Diabetes Research in Children Network), a multicenter consortium funded by the National Institutes of Health, studied 144 children with T1D and 72 children without diabetes. The participating children had an average age of 7 years at the beginning of the study and an average duration of illness of 2.4 years.
All study participants underwent structural magnetic resonance imaging (MRI) studies and age-appropriate cognitive tests. In patients with T1D, metabolic control was assessed using continuous glucose monitors (CGM) and hemoglobin A1C (HbA1C) tests. During the eight-year study period, up to four MRIs were performed for all participants, which measured the volume of white and gray matter in different brain regions. In the T1D group, the research team assessed the total cumulative hyperglycemic exposure since diagnosis.
The researchers found that total brain volume, gray and white matter volume, total IQ, and verbal IQ in the diabetes group were lower at 6, 8, 10, and 12 years compared to controls. Baseline differences persisted or increased over time, and brain volume and cognitive scores decreased as the lifetime HbA1C index and higher sensor glucose increased.
Although the differences in perception were small – about 4 IQ points – this magnitude is similar to other conditions affecting the brain. We know that T1D can cause complications in multiple organ systems, and our study extends previous research that suggests that variation in glucose levels in T1D can adversely affect brain development from childhood. “
Nelly Mauras, principal investigator of the study
“It’s really important to follow these findings in two ways. The first is to study these and other populations of people with T1D into young adulthood to see if and how brain and cognitive problems affect long-term education The second is to see whether tighter early control of blood sugar can stop or even reverse the brain and cognitive effects we observed in this study, “said Reiss, co-principal investigator of the study and Robbins Professor and Director of Interdisciplinary Brain Sciences at Stanford University School of Medicine.
Future research should investigate whether improved diabetes control could potentially reverse the brain changes observed, and such studies could also follow people with T1D into young adulthood to determine if and how brain and cognitive problems affect long-term education and training affect professional outcomes.
The DirecNet consortium includes the Nemours Children’s Health System Jacksonville, Florida; the Stanford University School of Medicine; Washington University, St. Louis; University of Iowa; and Yale University.
Mauras, N. et al. (2021) Effects of Type 1 Diabetes on the Developing Brain in Children: A Longitudinal Study. Diabetes treatment. doi.org/10.2337/dc20-2125.