Background: To investigate the national trend in prescription of first-line non-insulin antidiabetic agents and the annual total medical costs since the first prescription in Japanese patients with type 2 diabetes. Materials and Methods: Using the National Database of Health Insurance Claims and Specific Health Check-ups of Japan (NDB), we calculated the proportion of each antidiabetic drug from fiscal year (FY) 2014 to 2017 and determined factors associated with drug selection in multivariable logistic regression analyses. The total medical costs (TMCs) in the first year after starting the drugs were calculated and factors associated with the costs were also determined. Results: Among 1,136,723 newly-prescribed patients, dipeptidyl peptidase-4 inhibitors (DPP4i) were most prescribed (65.1%) followed by biguanides (15.9%) and sodium-glucose co-transporter-2 inhibitors (SGLT2i) (7.6%). SGLT2i use increased markedly, as was biguanide gradually increased and other drug use decreased during the study period. Biguanides were not prescribed at all in 38.2% of non-certified facilities by the Japan Diabetes Society. TMCs [adjusted mean, 95% CI] were lowest in biguanides [$4638, 4591-4686] followed by thiazolidinediones [$4670, 4546-4794], moderate in SGLT2i [$5383, 5297-5468] and DPP4i [$5583, 5550-5617], highest in glucagon-like peptide 1 receptor agonist [$8596, 7532-9661] after adjusting for covariates including age and comorbidities. FY, age, gender, type of insurance, facility, number of beds, and comorbidities were associated with drug choice and medical costs in the model. There was wide regional variation in initial choice of antidiabetic drugs but not in the TMCs. Conclusions: Unlike in Europe and the US, DPP4i stands as a first-line treatment in Japan. The wide variation in the drug choice by facility and prefecture may suggest the need to create a new strategy such as algorithms that facilitate appropriate drug selection in Japan. Disclosure R. Bouchi: None. T. Sugiyama: None. A. Goto: None. K. Imai: None. N. Ihana-sugiyama: None. M. Ohsugi: Other Relationship; Self; Kyowa Kirin Co., Ltd., Research Support; Self; Abbott Japan Co., Ltd., Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly Japan K. K., Mitsubishi Tanabe Pharma Corporation, MSD K. K., Novartis Pharma K. K., Novo Nordisk Pharma Ltd., Sanofi K. K., Sumitomo Dainippon Pharma Co., Ltd. T. Yamauchi: Other Relationship; Self; Abbott Japan LLC, Astellas Pharma Inc., AstraZeneca K. K., Daiichi Sankyo Company, Limited, Eli Lilly Japan K. K., Kissei Pharmaceutical Co., Ltd., Kowa Company, Ltd., Kyorin Pharmaceutical Company, Limited, Kyowa Kirin Co., Ltd., Merck Sharp & Dohme Corp., Mitsubishi Tanabe Pharma Corporation, Nippon Boehringer Ingelheim Co. Ltd., Novo Nordisk Pharma Ltd., Ono Pharmaceutical Co., Ltd., Sanofi K. K., Sanwa Kagaku Kenkyusho, Sumitomo Dainippon Pharma Co., Ltd., Taisho Pharmaceutical Co., Ltd., Takeda Pharmaceutical Company Limited, Research Support; Self; Aero Switch, Asahi Mutual Life Insurance Company, Bayer Yakuhin, Ltd., Mitsubishi Corporation Life Sciences Limited, NIPRO Medical Corporation, NTT Docomo Inc., Shionogi & Co., Ltd., Tosoh Corporation. T. Kadowaki: Other Relationship; Self; Asahi Mutual Life Insurance Company, MSD Corporation, Nippon Boehringer Ingelheim Co. Ltd., Novo Nordisk Pharma Ltd., Takeda Pharmaceutical Company Limited, Research Support; Self; Daiichi Sankyo Company, Limited, Eli Lilly Japan K. K., Kyowa Kirin Co., Ltd., Mitsubishi Tanabe Pharma Corporation, MSD Corporation, Novo Nordisk Pharma Ltd., Ono Pharmaceutical Co., Ltd., Sanofi K. K., Sumitomo Dainippon Pharma Co., Ltd., Takeda Pharmaceutical Co., Speaker’s Bureau; Self; Astellas Pharma Inc., AstraZeneca, Daiichi Sankyo Company, Limited, Eli Lilly Japan K. K., Kowa Company, Ltd., Kyowa Kirin Co., Ltd., Mitsubishi Tanabe Pharma Corporation, MSD Corporation, Nippon Boehringer Ingelheim Co. Ltd., Novo Nordisk Pharma Ltd., Ono Pharmaceutical Co., Ltd., Sanofi K. K., Sanwa Kagaku Kenkyusho, Sumitomo Dainippon Pharma Co., Ltd., Taisho Pharmaceutical Co., Ltd., Taisho Pharmaceutical Co., Ltd. K. Ueki: Advisory Panel; Self; Abbott Japan Co., Ltd., AstraZeneca K. K., Bayer Yakuhin, Ltd., Novo Nordisk Pharma Ltd., Poxel SA, Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Daiichi Sankyo, Eli Lilly Japan K. K., Japan Agency for Medical Research and Development, Japan Society for the Promotion of Science, Kyowa Kirin Co., Ltd., Mitsubishi Tanabe Pharma Corporation, Novo Nordisk Pharma Ltd., Ono Pharmaceutical Co., Ltd., Sanofi K. K., Sumitomo Dainippon Pharma Co., Ltd., Taisho Pharmaceutical Co., Ltd., Takeda Pharmaceutical Company Limited, Speaker’s Bureau; Self; Astellas Pharma Inc., AstraZeneca K. K., Boehringer Ingelheim Pharmaceuticals, Inc., Daiichi Sankyo, Eli Lilly Japan K. K., Kyowa Kirin Co., Ltd., Mitsubishi Tanabe Pharma Corporation, MSD K. K., Ono Pharmaceutical Co., Ltd., Sanofi K. K., Sumitomo Dainippon Pharma Co., Ltd., Taisho Pharmaceutical Co., Ltd., Takeda Pharmaceutical Company Limited. Funding Health and Labour Sciences Research Grants (20FA1016)