Objective: MOSAIc is a 2-year multi-national observational cohort study to identify factors associated with insulin intensification among patients already taking insulin· We describe baseline demographic, clinical, treatment, and psychosocial characteristics among 671 patients from China, Japan, and South Korea· Methods: Patient and physician data were collected at baseline· A linear regression model assessed the association between the Diabetes Distress Scale (DDS) and 10 covariates across countries· A higher score indicates severer distress· The 25-item Interpersonal Processes of Care Survey (IPC) assessed the patient-healthcare provider relationship, with a higher score representing more collaboration and communication· Results: Across countries type 2 diabetes mellitus duration and diabetic comorbidities differed, but body mass index and HbA1c did not vary significantly· Japanese patients used more non-insulin anti-diabetic drugs (1·80) than Chinese (0·63) or South Korean (0·84) patients· Exclusive use of basal insulin was very common in Japan and South Korea (over 55% of patients), while Chinese patients used mixed insulin alone (67%) more frequently· Chinese patients injected insulin more frequently each day (1·89) compared to Japanese (1·32) and South Korean (1·28) patients· In China, a higher HbA1c goal set by physicians and higher injection frequency were associated with higher DDS scores· In Japan, younger age was associated with a higher DDS score· Patients had slightly better relationships with their providers in South Korea (IPC = 3·2) versus China (2·9) and Japan (3·0)· Conclusion: We observed substantial variation in baseline characteristics· Forthcoming longitudinal data during the 2-year follow-up will clarify the observed associations and their relationships with insulin intensification and glycemic control·