The term ‘short-acting insulin’ is used for conventional human insulin (available as brands called Actrapid, Huminsulin-R etc).
The action of the short-acting insulin takes about 30 minutes to start, and the action lasts for 4-6 hours.
This insulin is generally given before meals and it has to be given atleast 30 minutes before taking the meal.
‘Rapidly acting insulin‘ is used for insulin that begins to act within 10 – 15 minutes and the action lasts for 4 hours. They are also called ‘insulin analogs’ or ‘designer insulins’.
Apidra (insulin glulisine), Humalog (insulin lispro) and Novorapid/NovoLog (insulin aspart) are some brands of rapidly acting insulin.
Since the gap between taking the insulin and the meal is shorter, it is more convenient to patients. However, it is also more expensive.
A new generation of insulin called ultra-fast acting insulin are also available. The first one of this generation of insulin is by the brand name of ‘FIASP’.
This insulin can be taken five minutes before the meal and can also be taken after the meal. It is the fastest acting insulin at present.