The use of sulphonylureas as a second-line substitution for metformin in type 2 diabetes is associated with increased rates of myocardial infarction (MI), all cause death and severe hypoglycaemia, a population-based cohort study has found. The study used data from the UK Clinical Practice Research Datalink (CPRD) to analyse a cohort of type 2 diabetes patients retrospectively. The CPRD contains medical records from more than 14 million patients registered at more than 680 general practices.