ObjectiveTo determine real-world trends in antidiabetic drug use, and persistence and adherence, in Japanese patients with type 2 diabetes mellitus (T2DM).DesignRetrospective evaluation of administrative claims data (2011–2015) using the Japan Medical Data Center (JMDC) and Medical Data Vision (MDV) databases.SettingAnalysis of two administrative claims databases for Japanese patients with T2DM.ParticipantsAdults (aged ≥18 years) with an International Classification of Diseases, 10th Revision code of T2DM and at least one antidiabetic drug prescription.Main outcome measuresTreatment patterns in untreated (UT) or previously treated (PT) patients receiving antidiabetic therapy; persistence with treatment at 12 months; adherence to treatment at 12 months.Results40 908 and 90 421 patients were included from the JMDC and MDV databases, respectively. The most frequently prescribed therapy at the index (first prescription) date was dipeptidyl peptidase-4 inhibitor (DPP-4i) in UT patients (JMDC: 44.0%, MDV: 54.8%) and combination therapy in PT patients (74.6%, 81.1%). Most common combinations were DPP-4i plus: biguanide (BG; 11.4%, 10.9%), sulfonylurea (SU; 8.4%, 11.0%) or BG+SU (7.8%, 9.1%). In UT or PT patients from either database whose index prescription was for any antidiabetic drug class(es) other than DPP-4i, the most frequent add-on or switch was to DPP-4i. 12-month persistence with index monotherapy was highest with DPP-4i and BG. Adherence was high (≥80%) for all monotherapy schedules, except insulin and glucagon-like peptide-1 agonist, and for the five most frequent two-drug and three-drug combinations. Persistence was greater in elderly UT patients and in those receiving ≤5 medications, but comparatively worse in UT patients with ≥3 index antidiabetic drug classes.ConclusionsThe findings indicate that DPP-4i is the most commonly used antidiabetic drug class in Japanese patients with T2DM, and persistence and adherence to this antidiabetic drug class are high.