Insulin is one of the oldest and best studied treatments for diabetes mellitus. Despite many improvements in the management of diabetes, the nonphysiological time-action profiles of conventional insulins remain a significant obstacle. However, the advent of recombinant DNA technology made it possible to overcome these limitations in the time-action profiles of conventional insulins. Used as prandial (e.g. insulin lispro or insulin aspart) and basal (e.g. insulin glargine) insulin, the analogues simulate physiological insulin profiles more closely than the older conventional insulins. If rapid-acting insulin analogues are used in the hospital, healthcare providers will need a new mind-set. Any error in coordination between timing of rapid-acting insulin administration and meal ingestion may result in hypoglycaemia. However, guidelines regarding in-hospital use of insulin analogues are few. The safety profile of insulin analogues is still not completely established in long-term clinical studies. Several studies have shown conflicting results with respect to the tumourigenic potential of this new class of agents. The clinical implications of these findings are not clear. Although novel insulin analogues are promising 'designer drugs' in our armamentarium to overcome some of the limitations of conventional insulin therapy, cost may be a limiting factor for some patients.