In the last 10 years, there has been considerable interest in the administration of insulin as part of the management of myocardial infarction. This review examines the clinical trials of insulin infusion for myocardial infarction in the era of reperfusion therapy, and discusses the implications of the recently completed HI-5 (Hyperglycaemia: Intensive Insulin Infusion In Infarction) study. The clinical trials of insulin therapy for myocardial infarction can be divided into those with a primary aim of delivering insulin (insulin focus), and those with a primary aim of achieving tight glycaemic control (glycaemia focus). The evidence suggests that protocols with an insulin focus do not improve the outcome of myocardial infarction. However, the trials with a glycaemia focus are inconclusive and it remains possible that glycaemic control is beneficial.