Objective To investigate whether severe hypocemia in young children with early-onset type 1 diabetes (T1DM) is associated with subsequent abnormalities in cognitive status.Study design Recruitment was from a large population-based database of children and adolescents with T1DM. Children and adolescents with early-onset T1DM (< 6 years) were eligible for the study. Diabetic individuals (n = 41) with a prospectively documented history of seizure or coma were compared with peers with no history of severe hypoglycemic events (n = 43). A comprehensive test battery of learning and memory was used together with intellectual and behavioral measures.Results No significant group differences were revealed on the intellectual, memory, or behavioral measures. Similarly, those participants with a history of early first seizure did not differ from their peers with no seizures. There were no significant group differences on the memo subtests that were examined given their potential sensitivity to compromised hippocampal function.Conclusions There was no clear evidence from this cohort that episodes of seizure or coma, even those occurring in very early childhood, resulted in broad cognitive dysfunction, nor was there evidence of specific memory difficulties at the time of testing in children and adolescents with early-onset T1DM.