209-OR: ADA Presidents' Select Abstract: Type 1 Diabetes and the Developing Brain—A Longitudinal Study of Brain Growth by the Diabetes Research in Children Network (DirecNet)

Background: The extent to which glycemic exposure adversely impacts the developing brain in young children with early-onset type 1 diabetes (T1D) is controversial.

Methods: As part of the multisite DirecNet Study, we performed structural MRI at three time points (baseline, 18 months and approximately 2.9 years after the second visit) in 137 children with T1D (age: 7.0 ± 1.7 years, lifetime average HbA1c: 8.0 ± 0.7%, and diabetes duration: 2.4 years at study entry) and 66 age-matched nondiabetic controls (7.0 1.8 years old). White matter (WM) and gray matter (GM) volumes in various brain regions-of-interest were determined by voxel-based morphometry (VBM). Total cumulative hyperglycemic exposure was determined as HbA1c area under the curve (lifetime A1c) from the time of diagnosis in T1D children.

Results: Children with T1D had slower growth of total cortical and subcortical GM and WM than the nondiabetic controls at all timepoints. Gray matter regions (frontal, temporal, subcortical, and occipital cortex) showed less growth in the T1D compared to the control group (p<0.05 family wise error (FWE)-corrected), as did white matter areas (temporal, parietal, and occipital white matter) (p<0.05 FWE-corrected). The occipital-cerebellar and basal ganglia regions appeared to be most vulnerable to the effects of T1D in children. The regions of slower growth were associated with higher lifetime A1c values (p<0.05 false discovery rate (FDR)-corrected).

Conclusion: This study demonstrates that children with early-onset T1D and worse glycemic control have slower cortical and subcortical GM and WM growth than nondiabetic controls, suggesting that hyperglycemia is detrimental to the developing brain during this critical period of rapid brain maturation. The long-term consequences of these early alterations in brain growth require further follow-up.