Insulin lispro, alone (Humalog) or as premixture (Humalog Mix25 or Humalog Mix50) is indicated for the treatment of hyperglycaemia in diabetes mellitus in many countries worldwide. It is a recombinant human insulin analogue and, except for the transposition of two amino acids, is identical to endogenous human insulin. Insulin lispro has a faster onset of action and shorter duration of activity than regular human insulin, and the time-action profile of insulin lispro mimics that of the physiological response of endogenous human insulin to food intake. In diabetic patients, from young children to the elderly, it has demonstrated postprandial blood glucose control similar to or better than that achieved with regular human insulin, without an increased risk of hypoglycaemia. In some trials, the risk of hypoglycaemia, including nocturnal episodes, was less in insulin lispro recipients than in regular human insulin recipients. Insulin lispro alone, or as a premixture with the longer-acting insulin neutral protamine lispro, can be administered immediately before or after meals. This convenient and flexible injection schedule may enable patients, including those with a non-routine lifestyle or unpredictable eating or exercising habits, to achieve the tight glycaemic control required to minimise long-term complications of diabetes and contributes to patient satisfaction with treatment.