These studies have defined T2DM subgroups using clinical variables typically assessed in secondary care settings, including measures of insulin secretion and resistance (determined using C-peptide and glucose assays), to delineate subgroups and their likely aetiology.2–4,7 However, in the UK, the majority of T2DM management takes place in primary care settings, where these investigations are rarely performed. The gene discussed is INS; the disease is type 2 diabetes mellitus.