Central diabetes insipidus (CDI) is a rare disease characterized by polyuria and polydipsia. Patients with CDI have been successfully treated with desmopressin administered either by intranasal instillation or oral tablets. Recently, a desmopressin orally disintegrating tablet (ODT) was approved as the first oral desmopressin tablet for CDI treatment in Japan. We conducted a retrospective single-center study of 15 Japanese CDI patients treated with desmopressin ODT therapy, which aimed to evaluate the efficacy and safety of switching to desmopressin ODT and to analyze the clinical factors that affect the desmopressin ODT dose in Japanese patients. The daily mean dose of desmopressin ODT was 104 ± 46.30 μg and the mean ratio of oral to nasal desmopressin dose was 17.0 ± 7.6, both of which are considerably smaller than those of previous dose-titration study. Moreover, the nasal spray group needed significantly smaller ratios of nasal to oral desmopressin than the nasal drop group (11.7 ± 6.5 vs 21.0 ± 5.5, p = 0.02). The ratio of oral to nasal desmopressin dose had a significant inverse correlation with the required nasal desmopressin dose. Multiple regression analysis demonstrated the ratios of nasal to oral desmopressin dose depended on intranasal formulations. In conclusion, desmopressin ODT was safe and effective in the treatment of Japanese adult CDI patients. When switching to ODT, we should care about the possibility that patients require smaller ODT doses than what was initially expected based on previously published data and also nasal formulations in terms of their differences of expected switching ratio.