ABSTRACT Glucose is the most important source of energy for proper brain development and functioning; therefore, any imbalance in glucose is associated with changes in neurodevelopment. Hypo- and hyperglycemia impact brain structure and functioning and cognitive abilities across the lifespan and it is well-established that older adults with type 1 diabetes (T1D) experience cognitive impairment. Indeed, individuals with T1D have a 65% increased risk for dementia later in life compared to 37% in those with type 2 diabetes. Increasing glucose metabolism during childhood is related to growth of healthy brain structures and connections; but for individuals with early childhood onset of T1D, decreases in brain structures and functions and lower neurocognitive abilities and IQ occur. Brain imaging studies of individuals with T1D demonstrate reductions in total brain volume and gray and white matter density in the cerebellum; and changes in the frontal, parietal, and temporal lobes; hippocampus; thalamus; and various structures in the occipital lobe. Individuals with T1D generally demonstrate challenges with mental flexibility, intelligence, memory, executive functioning, and processing speed with earlier age of onset, longer T1D duration, suboptimal glycemia, hypo- and hyperglycemia and extreme glycemic variability, and diabetic ketoacidosis serving as risk factors for worse cognitive performance, lower IQ, and brain structural changes. Studies focused on neuroimaging and neurocognition in the context of T1D biomarkers, social determinants of health, sleep and psychological, social, and school functioning with children with new-onset T1D in the United States are extremely sparse. Therefore, there is an urgent need to address these gaps in the extant literature to identify opportunities to prevent or mitigate cognitive challenges across the lifespan. The overarching goals of the Diabetes Brain and Cognitive Development – Type 1 Diabetes (DBCD-T1) study are to 1) understand the impact of T1D on brain and neurocognitive and psychosocial functioning; 2) examine risk and protective factors associated with T1D- related neurocognitive impact; and 3) assess associations of diabetes technologies and neurocognitive functioning in children with T1D. We will recruit n=160 prepubescent children with new-onset T1D and their caregivers from the Northwest, North Central, and Northeast districts of Florida, with sociodemographic characteristics representative of the US population of children with T1D. Study tasks include brain imaging and comprehensive neurocognitive and academic testing (e.g., IQ, memory, executive functioning, processing speed, reading, mathematics, writing); questionnaire completion (e.g., anxiety, depression, quality of life, resilience, fear of hypoglycemia, T1D family conflict, diabetes distress); and collection of biological (e.g., autoantibodies, C-peptide), sleep (actigraphy), and diabetes device and glycemic data (e.g., device downloads, A1C)...