Use of oral antidiabetic drugs in Japanese working-age patients with type 2 diabetes mellitus: dosing pattern for metformin initiators

Objective: To determine the pattern of antidiabetic drug use, with a particular focus on the metformin dose, among patients with type 2 diabetes mellitus (T2DM) in a Japanese working population. Methods: We used an administrative claims database linked to yearly health check-up data from large corporations. Data were collected for T2DM patients who began using an antidiabetic drug between 2014 and 2017 (n = 20,401). We evaluated the type of antidiabetic drug used and the characteristics of the patients using each type of drug. Among the metformin users, we assessed the titration in its dose or treatment during the 12 month period after initiation at 3 month intervals. Results: Among 20,401 new antidiabetic users, the most frequently used agents during the study period were dipeptidyl peptidase-4 inhibitors (DPP4is; 47.4%), followed by biguanides (18.5%) and sodium glucose cotransporter-2 inhibitors (SGLT2is; 6.7%). Most patients who initiated with metformin were prescribed 500 mg or less daily (72.9%); only 2.0% were prescribed a daily dose of >1000 mg. Moreover, 27% remained on the same daily dose during the 1 year follow-up, whereas another 29.9% discontinued their antidiabetic treatment altogether. Conclusions: A unique pattern of prescription was observed amongst Japanese patients with T2DM, and DPP4is, rather than metformin, were predominantly used as the first-line treatment. SGLT2is were infrequently prescribed. Metformin was prescribed at a daily dose of ≤500 mg in many patients. Greater efforts are needed to assess the comparative effectiveness of these treatment strategies.