Diabetes self-management education through peer support has been beneficial, especially in regions with limited medical resources. Studying the effects of education offered by trained peers of patients will facilitate tailoring the peer-led education programs to the regions’ specific needs. Here, we evaluated changes in diabetes-related indicators in Filipino patients who received a peer-led education. We used data on 23 patients (age, 67.83 ± 6.69 years; 82.6% female) who participated in all five surveys performed every 6 months from March 2017 to March 2019. After the second survey until the end of this study, the participants were educated in diabetes self-management by their 13 peers who previously had received the training in diabetes self-management. Participants’ knowledge of diabetes and the related ‘cause, risk factors, nature of diabetes and complications’ subindicator were greater on all surveys after starting the peer-led education compared with those on the second survey (i.e. before starting the education); these values did not differ between the first two surveys. Because increasing patients’ knowledge can enhance their ability to self-manage their disease and thus improve their quality of life, strategies to expand patients’ knowledge about diabetes should be included when organizing peer-led education in regions with limited medical resources.