Type 1 diabetes mellitus has a large psychosocial impact on children and their families. This study's primary aim was to investigate whether the COVID-19 pandemic affects the psychosocial impact of T1DM and glycaemic control. During the 2020 lockdown, New South Wales residents were not allowed to leave home except for essential activities. After 3 months, children with T1DM and their parents were invited to complete online questionnaires. Data on glycaemic control were extracted from the children's clinical records with informed consent. Descriptive and comparative statistics were used to analyse the responses. Out of 149 families, 99 responses were received, with 92 participants identified. Comparable proportions of parents (56%) and children (45%) were anxious about the child's increased risk of contracting severe illness due to COVID-19. Most responses from parents and children were closely correlated (r > 0.5, P ≤ 0.001) There was no consistent effect of lockdown on HbA1c levels, but there was a significant inverse correlation between HbA1c levels and parents' perception of the child having clear and concrete goals for diabetes care (r = -0.25, P < 0.05). The HbA1c also correlated positively with the child feeling depressed and alone with their diabetes when isolated (r = 0.36, P = 0.02). Despite life-style changes and a negative psychosocial impact, we did not find objective evidence of any detrimental impact of the lockdown on diabetic control. However, higher HbA1c correlated with children feeling more depressed and alone. There was a comparable frequency of anxiety concerning the risk of severe COVID illness in children and their parents.