To improve insulin therapy, new insulin analogues have been developed. Two fast-acting analogues with a more rapid onset of effect and a shorter duration of action combined with a low day-to-day variation in absorption rate are now available. Despite this favourable time-action profile most studies have not been able to show any improvement in overall glycaemic control with the fast-acting analogues. A reduced post-prandial increase in blood glucose has been found in all studies, whereas between 3 and 5 h after the meal and during the night an increased blood glucose level is the normal course. This is probably the main explanation for the absence of improvement in overall glycaemic control when compared with regular human insulin. A tendency to a reduction in hypoglycaemic events during treatment with fast-acting analogues has been observed in most studies. Recent studies have indicated that NPH insulin administered several times daily at mealtimes can improve glycaemic control without increasing the risk of hypoglycaemia. The fast-acting analogues are now also available as insulin mixed with NPH. Insulin glargine is a new long-acting insulin which is soluble and precipitates after injection, resulting in a long half-life with a residual activity of about 50% 24 h after injection. Insulin glargine is a peakless insulin and studies in both type 1 and type 2 diabetic patients indicate that glargine improves fasting blood glucose control and reduces the incidence of nocturnal hypoglycaemia. Surprisingly, the new fast-acting analogues have not achieved the expected commercial success, which emphasises the need for new strategies for basal insulin supplementation, exercise, diet and blood glucose monitoring.