Background: Poor glycemic control in patients with diabetes mellitus can increase associated complications and mortality. We use the telehomecare system in patients with diabetes and investigate the associated impact in clinical practice. Materials and Methods: The purpose of the study is to examine the effectiveness of the telehomecare system on diabetic self‑care. The telehomecare system incorporated into the daily care program in the experimental group. A cloud health‑care platform designed for information storage and exchange be constructed and monitored by case managers. Comprehensive care instructions and in‑time consultation in case of abnormalities were provided. The patients in the control group adopted conventional care program. Self‑care questionnaires were completed by both groups before and after the study. All participants measured before the experiment and at 4 months after. Results: The participants were 117 patients (including 56 at the experimental and 61 at the control group), which recruited from a community hospital in New Taipei city, Taiwan. In two‑way mixed design ANCOVA, in self‑care behaviors, there are significant differences between two groups. The outcome of experimental group is superior to the control group both in posttest. However, there is no significant difference between two groups in subscales of foot care and athletics care. Moreover, there is no delayed effect in self‑care behaviors of drug adjustment and blood sugar surveillance. Conclusions: This observational study revealed early intervention model to the health education strategy, the telehomecare might strengthen self‑care behaviors of the participants. To the future study, we can put emphasis on the diabetes mellitus patient’s foot care and exercise behaviors. The telehomecare model could also become the important health‑care policy for the government in the future.