AimTo examine psychosocial and behavioural impacts of the novel coronavirus disease 2019 (COVID‐19) pandemic and lockdown restrictions among adults with type 2 diabetes.MethodsParticipants 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).ResultsAmong 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.ConclusionsCOVID‐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.