Diabetes self-management is an essential part of diabetes care. Although several personality traits were reportedly associated with self-management behaviors or glycemic control in Western countries, clinical evidence of such an association is still sparse, especially among Asian patients with diabetes. Thus, we aimed to clarify the associations among personality, self-management behaviors, and glycemic control in Japanese patients with T2DM. Analyzed were 510 Japanese patients with T2DM (62.2 ± 11.2 y; 57% men) with available information on personality (assessed by NEO Five-Factor Inventory), diabetes self-management activities (assessed by the Japanese version of Summary of Diabetes Self-Care Activities), body mass index (BMI), and HbA1c. Coefficient of correlation indicated that those with high scores for neuroticism, as well as low scores for conscientiousness, had lower levels of diet (neuroticism r = -0.14, P<0.05; conscientiousness r = 0.14, P<0.001) and physical activity (neuroticism r = -0.13, P<0.05; conscientiousness r = 0.15, P<0.001) self-management than those without such scores. There was no significant trend in medication adherence according to personality traits. Structural equation modeling showed that HbA1c was negatively associated with conscientiousness (standardized path coefficients = -0.024, P<0.05). Conscientiousness was significantly associated with higher self-management scores on diet and physical activity and was directly and indirectly (via BMI) related to HbA1c levels. Our results showed that Japanese patients with high conscientiousness levels had better glycemic control via favorable adherence to diet and physical activity but not medication adherence than those with lower conscientiousness levels. Evaluation of personality traits could identify patients likely to exhibit good/poor diabetes self-management care. This might be helpful in providing effective and efficient patient education. Disclosure S.Y. Morikawa: None. K. Fujihara: None. M. Hatta: None. Y. Takeda: None. D. Ishii: None. J. Yachida: None. C. Horikawa: None. M. Kato: None. H. Maegawa: Research Support; Self; Antares Pharma, Boehringer Ingelheim Pharmaceuticals, Inc., Daiichi Sankyo Company, Limited, Mitsubishi Tanabe Pharma Corporation, Takeda Pharmaceutical Company Limited. Speaker's Bureau; Self; Astellas Pharma Inc., Boehringer Ingelheim Pharmaceuticals, Inc., Daiichi Sankyo Company, Limited, Merck Sharp & Dohme Corp., Mitsubishi Tanabe Pharma Corporation, Takeda Pharmaceutical Company Limited. H. Sone: Research Support; Self; Astellas Pharma Inc., Boehringer Ingelheim Pharmaceuticals, Inc., Daiichi Sankyo Company, Limited, Kowa Pharmaceutical Europe Co. Ltd., Kyowa Hakko Kirin Co., Ltd., Novo Nordisk Inc., Ono Pharmaceutical Co., Ltd., Taisho Pharmaceutical Co., Ltd., Takeda Pharmaceutical Company Limited, Teijin Pharma Limited.