Background: Infancy-onset diabetes is largely monogenic before 6 months of age, whereas autoimmune type 1 diabetes is more likely from 6-12 months of age. As the most common neonatal diabetes, patients with KATP channel mutations exhibit a spectrum of neurodevelopmental disability that is largely related to brain expression of mutated channels. It is not known how glycemic dysregulation of any type of early-onset diabetes may affect brain development. Methods: Subjects included from UChicago Monogenic Diabetes Registry with diabetes diagnosed under a year of age currently aged 4-20 years and unaffected sibling controls. Known KATP channel mutations or other rare causes affecting brain development were excluded. Measures of intellectual function (IF), executive function (EF), visual motor integration (VMI) and academic achievement (AA) were utilized (Table 1). A two-sample t-test was conducted comparing each group assuming unequal variance. Results: Comprehensive testing was completed for those with infancy-onset diabetes and siblings (Table 1). There were no significant differences on any measure, though mean scores trended lower in the affected group. Conclusion: Our findings show no difference in IF, EF, VMI, AA in children diagnosed with diabetes in infancy compared to their unaffected siblings. Our conclusions are limited due to a small sample size; differences may be subtle and require a larger sample size to be identified. Disclosure M. McCauley: None. A.M. Denson: None. L.R. Letourneau-Freiberg: None. M.N. Scott: None. S.W. Greeley: None. Funding American Diabetes Association (1-17-JDF-008 to S.A.W.G.); National Institute of Diabetes and Digestive and Kidney Diseases (R01DK104942, P30DK0205950); National Center for Advancing Translational Sciences (UL1TR002389)