short-acting insulin

Last reviewed 11/2021

Replaced by insulin analogues as the quickest acting insulins.

Often known as soluble or ‘regular’ or 'neutral' insulin.

Some features of short-acting or neutral insulins include:

  • peak 2-6 hours after subcutaneous injection
  • tendency to form hexamers in the insulin vials - these dissociate slowly leading to reduction in absorption rate
  • onset of action 30–60 mins
  • peak 2–4 hours
  • in some individuals can have an effect 8-12 hours after administration of injection
  • injected 20-30 minutes before a meal
  • may result in postprandial and nocturnal hypoglycaemia because of long-lasting effects
  • in some patients short-acting insulins remain the optimum quick-acting insulin
  • examples Human Actrapid®, Humulin S®, Insuman® Rapid? (also porcine and bovine equivalents of these)
  • note that some of these insulins are also licensed for use in continuous subcutaneous insulin infusion i.e. insulin pumps (1)

Examples include human actrapid.


  1. MeRec Bulletin 2007;17(4).
  2. Prescriber 2001;12 (14): 43-50