IntroductionTo present longitudinal data from the Real-world Observational Study on Patient Outcomes in Diabetes (RESPOND) in Japan.Research design and methodsIn this multicenter, prospective, observational cohort study, patients with type 2 diabetes mellitus (T2DM) newly initiated on monotherapy were followed up for 2 years. Primary outcomes included changes in treatment pattern over time, target hemoglobin A1c (HbA1c) attainment and treatment satisfaction per Oral Hypoglycaemic Agent Questionnaire (OHA-Q).ResultsAmong 1474 enrolled patients (male, 62.1%; mean age, 59.7 years; HbA1c, 8.08%), the oral antidiabetic drug (OAD) monotherapy prescription rate decreased to 47.2% and that of 2 and ≥3 OADs increased to 14.8% and 5.4% at 24 months, respectively. Switch/add-on OAD was associated with higher HbA1c and body mass index (BMI), baseline OAD being non-dipeptidyl peptidase-4 inhibitor (DPP-4i)/non-sodium glucose cotransporter-2 inhibitor (SGLT2i), diabetes complications, no comorbidities and consulting a diabetes specialist. The mean (SD) HbA1c (%) was 6.73 (0.85) at 24 months. Higher HbA1c, diabetes complications, cardiovascular disease, being employed, no hypertension and younger treating physician were associated with ≥2 OAD classes prescription or target HbA1c non-attainment at 24 months. OHA-Q subscale scores were significantly higher in patients achieving (vs not achieving) target HbA1c and in those continuing monotherapy (vs combination therapy). Baseline age (<65 years), sex (female), HbA1c, alcohol use, use of non–DPP-4i OADs or non-T2DM drugs, diabetes complications and cardiovascular disease had a significant negative impact, while EuroQol five-dimensional five-level and Summary of Diabetes Self-Care Activities-specific diet scores, BMI and unemployment had a significant positive impact on OHA-Q scores at 24 months.ConclusionsPrimary outcomes show real-world treatment patterns and glycemic control over 2 years in patients with T2DM newly initiated on OAD monotherapy in Japan. Key factors associated with durability of initial monotherapy, target achievement or treatment satisfaction included baseline HbA1c, comorbidity and initial OAD choice.