To examine psychosocial and behavioural impacts of the novel coronavirus disease 2019 (COVID-19) pandemic and lockdown restrictions among adults with type 2 diabetes.Participants enrolled in the PRogrEssion of DIabetic ComplicaTions (PREDICT) cohort study in Melbourne, Australia (n = 489 with a baseline assessment pre-2020) were invited to complete a phone/online follow-up assessment in mid-2020 (i.e., amidst COVID-19 lockdown restrictions). Repeated assessments that were compared with pre-COVID-19 baseline levels included anxiety symptoms (7-item Generalised Anxiety Disorder scale [GAD-7]), depressive symptoms (8-item Patient Health Questionnaire [PHQ-8]), diabetes distress (Problem Areas in Diabetes scale [PAID]), physical activity/sedentary behaviour, alcohol consumption and diabetes self-management behaviours. Additional once-off measures at follow-up included COVID-19-specific worry, quality of life (QoL), and healthcare appointment changes (telehealth engagement and appointment cancellations/avoidance).Among 470 respondents (96%; aged 66 ± 9 years, 69% men), at least 'moderate' worry about COVID-19 infection was reported by 31%, and 29%-73% reported negative impacts on QoL dimensions (greatest for: leisure activities, feelings about the future, emotional well-being). Younger participants reported more negative impacts (p < 0.05). Overall, anxiety/depressive symptoms were similar at follow-up compared with pre-COVID-19, but diabetes distress reduced (p < 0.001). Worse trajectories of anxiety/depressive symptoms were observed among those who reported COVID-19-specific worry or negative QoL impacts (p < 0.05). Physical activity trended lower (~10%), but sitting time, alcohol consumption and glucose-monitoring frequency remained unchanged. 73% of participants used telehealth, but 43% cancelled a healthcare appointment and 39% avoided new appointments despite perceived need.COVID-19 lockdown restrictions negatively impacted QoL, some behavioural risk factors and healthcare utilisation in adults with type 2 diabetes. However, generalised anxiety and depressive symptoms remained relatively stable.