'Online boundary-work': How people with diabetes negotiate what counts as legitimate knowledge in Facebook peer support groups

People with chronic conditions such as diabetes use social media to interact with peers. While these online interactions allow them to exchange advice and gain insight into how others cope with their condition, concerns about 'misinformation' being shared are persistently raised, especially among medical professionals. Rather than assessing whether information shared on social media is 'correct' from a clinical perspective, we explore how people with diabetes negotiate what counts as legitimate knowledge as they interact in Facebook groups. Empirically, we draw on a six-month observation of interactions in two Danish Facebook groups for people with type 1 and 2 diabetes, including a data sample of 300 posts and 7797 comments. Observations were carried out in 2021. Guided by the concept of boundary-work (Gieryn, 1983), we analyse how members of the Facebook groups demarcate legitimate knowledge from what they deem illegitimate, enacted as they scrutinise peer advice and knowledge claims. We refer to this ongoing process as 'online boundary-work' and draw out three distinct negotiations, specifying how group members (a) recognise sharing of personal experiences as useful but do not necessarily accept them as valid forms of self-management advice, (b) support each other in evaluating medical issues but delegate certain treatment decisions and responsibility to professionals and (c) do not necessarily agree on the most accurate answer but mobilise scientific or professionally managed sources to legitimise or question claims. Our work contributes to the science and technology studies (STS) literature on how social media facilitates a collective space for people with chronic conditions to 'diagnose' issues in daily self-management and reflect on solutions, especially through sharing personal experiences. By demonstrating how these activities involve an ongoing, collective task of negotiating what counts as legitimate knowledge, we elucidate the effort people with diabetes put into upholding peer support groups as digital spaces for solidarity and knowledge useful to daily self-management. However, as we highlight, online boundary-work does not necessarily result in consensus, prevent certain types of advice from being shared or guarantee that answers are considered useful to members or 'correct' from a clinical perspective.