From tiny acorns mighty acorns grow. In Paul Buchanan’s case, that tiny acorn was the idea to create an online ‘agora’ for people with diabetes – a meeting place where ideas and experiences could be exchanged freely and responsibly, and a focal point for a nascent peer support network. Paul’s vision is a network of online communities worldwide united by diabetes through social media. The key difference between that vision and the mighty oak is the time they take to grow. Every week, the UK’s diabetes online community that Paul started grows dramatically, and the debates it generates reach extraordinary numbers of people – to the point that they became a globally ‘trending topic’ on Twitter. With the idea already being taken up in a number of other countries, including Australia, the USA and Germany, a global network is far from a distant hope. In this article, the community’s founder explains.