medwireNews: Improved glycemic control with hybrid closed-loop insulin delivery may facilitate the typical neurodevelopmental changes that occur during adolescence for those with type 1 diabetes, suggests a proof-of-concept trial.
Across just 6 months of use, adolescents with type 1 diabetes showed larger structural brain changes if using a closed-loop system rather than standard care, as well as improved cognitive function, the researchers report in Nature Communications.
The 42 adolescents in the study were randomly assigned to use either hybrid closed-loop insulin delivery with the Medtronic MiniMed 670G system or standard care for 6 months, resulting in an average 16.43% improvement in time in range (TIR; 70–180 mg/dL, 3.9–10.0 mmol/L) in the former versus the latter group. This was statistically significant and driven by a reduction in the time spent in hyperglycemia, both during the day and at night.
Over the study period, adolescents using the closed-loop system had a significantly greater reduction in total cortical surface area than those using standard care, of 12.56 versus 5.19 cm2.
They also had larger reductions in average cortical thickness and gray matter volume that did not reach statistical significance, despite a moderate effect size for both. There were, however, significantly greater reductions in a region comprising the left frontal lobe and left superior temporal cortex.
Allan Reiss (Stanford University, California, USA) and co-researchers note that reductions in these measures “are readily observable in typically developing adolescents,” which is why they chose them as their primary endpoints.
The team also looked at white matter volume, which typically increases during adolescence, but found no between-group differences over the study period. However, the closed-loop group had significantly larger increases in white matter fractional anisotropy than the standard care group, indicating greater increases in fiber density.
These structural brain changes were accompanied by improvements in cognitive outcomes, with adolescents in the closed-loop group also having a significantly greater improvement in the WASI-II Perceptual Reasoning Index score versus the standard care group, at 6.10 versus 2.05.
This measure “reflects nonverbal abilities and visuomotor skills and, as such, is a measure of a person’s ability to reason and think flexibly,” explain the researchers.
“Cognitive test scores of this type are typically stable during childhood and adolescence and thus a 6-point increment is likely meaningful and outside the expected variation associated with measurement error.”
Although there were no overall differences in Verbal Comprehension Index or Full-Scale IQ scores, an exploratory analysis showed greater improvements with closed-loop control versus standard care in a subset of participants with above-median glucose control at baseline.
“This finding suggests that adolescents with [type 1 diabetes] who have better long-term glycemic control may have a greater capacity to improve standardized IQ scores in response to interventions such as hybrid closed-loop devices,” say Reiss and team.
“This finding also emphasizes the potential importance of rigorous glycemic control throughout a child’s lifetime.”
The study results overall indicate that closed-loop insulin delivery facilitates “brain development more congruent with nondiabetic adolescent populations,” say the researchers.
They add: “The fact that significant changes can be observed over a period of six months offers hope that insults to the developing adolescent brain might be preventable or even reversible with rigorous glucose control.”
medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2022 Springer Healthcare Ltd, part of the Springer Nature Group