Background: the context and purpose of the studyDiabetes mellitus is one of the four priority non-communicable diseases worldwide. It can lead to serious long-term complications and produces significant costs. Due to the chronicle character of the disease, it requires continuous medical treatment and good therapy adherence of those suffering. Therefore, diabetes self-management education (DSME) (and support DSMES) plays a significant role to increase patient’s self-management capacity and improve diabetes therapy. Research indicates that these outcomes might be difficult to maintain. Consequently, effective strategies to preserve the positive effects of DSMES are needed. Preliminary results show that peer support, which means support from a person who has experiential knowledge of a specific behaviour or stressor and similar characteristics as the target population, is associated with better outcomes in terms of HbA1c, cardiovascular disease risk factors or self-efficacy at lower cost compared to standard therapy. Peer-supported instant messaging services (IMS) approaches have significant potential for diabetes management because support can be provided easily and prompt, is inexpensive, and needs less effort to attend compared to standard therapy. The major objective of the study is to analyse the impact of a peer-supported IMS intervention in addition to a standard diabetes therapy on the glycaemic control of type 2 diabetic patients. Methods: how the study will be performedA total of 205 participants with type 2 diabetes mellitus will be included and randomly assigned to intervention or control group. Both groups will receive standard therapy, but the intervention group will participate in the peer-supported IMS intervention, additionally. The duration of the intervention will last for seven months, followed by a follow-up of seven months. Biochemical, behavioural and psychosocial parameters will be measured before, in the middle, and after the intervention as well as after the follow-up.Discussion: a brief summary and potential implicationsDiabetes mellitus type 2 and other non-communicable diseases put healthcare systems worldwide to the test. Peer-supported IMS interventions in addition to standard therapy might be part of new and cost-effective approaches to support patients independent from time and place.Trial registration: If your article reports the results of a health care intervention on human participants, it must be registered in an appropriate registry and the registration number and date of registration should be in stated in this section. If it was not registered prospectively (before enrollment of the first participant), you should include the words 'retrospectively registered'. See our editorial policies for more information on trial registration.ClinicalTrials.gov Identifier: NCT04797429Date of registration: 15 March 2021