The number of patients with diabetes continues to increase in Japan, which means that education in disease management is important. However, there have been few investigations into the importance of hospital pharmacists performing outpatient education for diabetes mellitus in Japan. In the diabetes outpatient department of Kitakyushu City Moji Hospital, a pharmacist commenced patient education using check sheets before patients saw the physicians from 2012. We divided the patients into groups with an increase or decrease of hemoglobin A1c (HbA1c) level after 6 months from the start of patient education. To assess the factors related to a decrease of HbA1c level, we compared background factors, and laboratory values between these two groups. In the patients whose HbA1c level decreased, the level was high at the start of patient education and they had less knowledge about their medications. To evaluate the impact of this patient education, we compared HbA1c values before patient education and after 6 months to determine the eŠect of providing education in the diabetes outpatient department. In the HbA1c8% group, the HbA1c level decreased signiˆcantly during 6 months of patient education. These results suggest that patient education by hospital pharmacists can be eŠective if HbA1c level is high at the start of education. This is theˆrst report about the usefulness of patient education by a hospital pharmacist for improvement of HbA1c level in diabetic outpatients in Japan.