Reclassifying Insulins
Insulins have hitherto been distinguished as clear (short-acting) and cloudy (long-acting). However the introduction of glargine, which is a clear long-acting insulin, has prompted the need for reclassification. In view of the increasing emphasis on intensive insulin therapy using basal-bolus regimens, a new, simple, pragmatic classification is suggested in which insulins are categorised according to the timing and purpose of administration: basal (maintenance), bolus (meal) and biphasic (mixed).

The evolution of insulin therapy ( Table 1 ) has witnessed the introduction of several different types of insulin preparations which have formed the basis for several classification categories. Historically this has involved the concentration of the insulin, time course of action, degree of purity, visual characteristics and species of origin. The expanding range of insulin preparations with different pharmacokinetic and pharmacodynamic properties, including the latest generation of analogue insulins, has brought into focus the need to formulate an up-dated pragmatic and practical classification of insulins.