The COVID-19 pandemic has a serious effect on community-based care for the elderly with diabetes in terms of the health promotion campaign, and continuity of Care. This study aimed to 1) study the situation and outcomes of modified diabetic care in the elderly (DCiE) during the COVID-19 pandemic, 2) develop and evaluate the DCiE system after the COVID-19 pandemic for primary healthcare centers (PMCs) by including the stakeholders involved in the development process, and 3) analyze proposed policy for the DCiE system during and after the COVID-19 pandemic. The mixed method methodology which consisted of the critical participatory action research and the survey research were utilized to conduct the study in order to compare the effects of the DCiE system during the pre-design, design, and post-design phases. One province of each of the 11th and 12th health regions was selected to participate in the study. The findings showed that the selected PMCs adjusted healthcare services during this pandemic situation as followings: 1) the extended follow-up appointment for elderly with diabetes based on their ability to control glucose levels, 2) the community-based chronic care focused on self-care management, and 3) the establishment of home delivery of medication based on their previous regimens. The DCiE system after the COVID-19 pandemic for PMCs integrated four significant components of the chronic care model as the followings: 1) The community resource 2) The process screening system 3) the knowledge and skills 4) the tool for two-ways health communication. The DCiE system was implemented throughout three interrelated subsystems which were 1) the new normal home healthcare system (Assess, Analyze, Implement, Improve) with the Thaichana-DM application, 2) the health information system for decision making, and 3) the integration of outcomes and outcome management. The effects of the DCiE revealed that 1) the mean capillary blood glucose at the postintervention significantly reduced, compared to the mean baseline (p <.001), 2) hemoglobin A1C levels at the post-intervention in the elderly with diabetes were lower than those at the pre-intervention (p < .001), and 3) the overall quality of life score among these participants was at the average level The policies were proposed 3 levels based on the significant findings of the study that consisted of 1) Upstream management, public health authorities in the area jointly developed health literacy in diabetes management focusing on clinical severity level analysis and decision-making with participatory and the prevention of COVID-19 for patients and caregivers by using a new-normal modeled home visit (2AI) 2) Midstream management, policy-level agencies in the province and local government organizations should support undertaken to have personnel with the ability to view health information systems covering both software and peopleware competency, and access to WIFI during home visits. 3) Downstream management, PMCs should monitor and assess clinical outcomes in the elderly with diabetes, covering the severity of clinical symptoms, and quality of life and continually develop plans. These proposed policies will be the supportive and driven mechanism for developing the effective DCiE system in both normal circumstances and the COVID-19 pandemic situation.