Purpose

The investigators have previously studied a group of young children with T1D using brain MRI, age-appropriate neurocognitive testing and continuous glucose monitoring, followed for 18 months. The investigators observed significant differences in gray matter volumes and white matter microstructure in the children with diabetes as compared to controls. These differences appeared to increase over time, with slower rates of brain growth in the T1D group (Mazelli, et al, Diabetes 2014; Barnea-Goraly, et al, Diabetes Care 2014; Mauras, et al, Diabetes 2015). In this new protocol the investigators will include the same children with T1D and healthy controls previously studied and recruit new similar subjects to replace those lost by attrition. The investigators will be using structural and functional brain MRI, neurocognitive testing and measures of glycemic control, to determine if changes in the brain persist or worsen over longitudinal follow up, and whether these changes are associated with measures of glycemic control and neurocognitive metrics as these children grow and progress through puberty.