By Serena Gordon
The study compared MRIs of the brain in kids with type 1 diabetes to age-matched children without the condition. Researchers also saw that areas of slower brain growth were associated with higher average blood sugar levels.
"We found significant detectable and persistent differences in the volume of different brain areas that participate in a lot of cognitive functions. There was slower growth across the board in the brain," said Dr. Nelly Mauras, co-principal investigator of the study. She's chief of the division of pediatric endocrinology at Nemours Children's Health System in Jacksonville, Fla.
The researchers also tested the children's thinking and memory skills (cognitive function) and found a 5- to 7-point difference in IQ scores. "There are detectable differences in IQ, particularly verbal IQ and vocabulary," Mauras noted.
But Mauras stressed that while the data are concerning and suggest a need for even better blood sugar management, kids in the study were -- on average -- doing well in and out of school.
"There are plenty of smart kids with type 1 diabetes. But these data along with others show that the status quo [for blood sugar management] probably isn't good enough to prevent diabetes complications in the brain," she said.
Dr. Mary Pat Gallagher, director of the Pediatric Diabetes Center at NYU Langone Health in New York City, wasn't involved in the study, but was familiar with its findings. She noted that the study authors "weren't saying that these kids would be classified as cognitively impaired, but they did see subtle changes in the development of the brain."
For families living with type 1 diabetes, Gallagher said this study "is not something they should lose sleep over, but it does support recent recommendations that even in very young children, it's not just low blood sugar we need to be worried about, we want to achieve tight blood sugar control."
Type 1 diabetes is an autoimmune disease. It causes the body's immune system to mistakenly attack the insulin-producing cells. Insulin is a hormone that helps usher sugar from foods into the body's cells to be used as fuel.
Because the cells that make insulin are destroyed in type 1 diabetes, people with the disease must replace that lost insulin. This can be done with multiple daily shots. It can also be done using a small tube inserted underneath the skin that's attached to an insulin pump worn outside the body.
Replacing lost insulin is a difficult balancing act. Too little insulin results in high blood sugar levels, which can cause serious complications over time. Too much insulin can cause dangerously low blood sugar. Left untreated, low levels can cause someone to pass out, and in the most extreme cases, can result in death.
Gallagher noted that low blood sugar levels were long thought to be a bigger concern, especially in very young children. But she said the American Diabetes Association had recently changed its recommendations to focus more on tighter blood sugar control in young children, because this time could be a vulnerable period in brain development.
The current study included 138 children with type 1 diabetes from five medical centers across the United States. The study also included 66 age-matched children without diabetes for comparison.
The kids with type 1 diabetes were diagnosed between 4 and 7 years of age, Mauras said. When the study began, their average age was 7 years, and they had had diabetes for an average of 2.4 years.
All children had three MRIs: one when the study began, another 18 months later and then again nearly three years later. The researchers also gathered health information, such as average blood sugar control, and they conducted tests of thinking and memory skills.
While the study linked higher blood sugar levels with areas of slower brain growth, it's not yet clear if good blood sugar control will make a difference in brain volume. Mauras suspects it will.
She said it's also still unknown if the same changes would occur in children diagnosed at older ages. But research in adults with type 1 diabetes suggests that subtle cognitive differences exist, Mauras added.
The findings were presented Sunday at the American Diabetes Association meeting, in San Francisco. Findings presented at meetings are typically viewed as preliminary until they've been published in a peer-reviewed journal.