A 79-year-old female with type 2 diabetes and mild cognitive impairment (Clinical Dementia Rating score of 0.5) was supported with medication with regard to the daily requirements using a medication reminder device. Use of this device not only improved her medication adherence, hemoglobin A1c level, and self-confidence but also reduced caregiver's burden. For elderly patients with such diseases, loading the device with medication, providing advance notice before mechanical reminders for a short period after the device's activation, monitoring unused medication, and adjusting the timing of reminders according to users' daily routine, seemed to facilitate daily use of the device.