Insulin therapy revolutionised the management of diabetes mellitus when it was developed in the 1920's. It is still the only available treatment for type 1 diabetes mellitus (T1DM) and is widely used in type 2 diabetes mellitus (T2DM) where oral hypoglycaemic agents fail to gain adequate control.

It can sometimes seem daunting to understand the various types of insulin but it is important you have a basic grasp to avoid potential harm to patients.

Classification of insulin

By manufacturing process
  • porcine: extracted and purified from pig pancreas
  • human sequence insulin: either produced by enzyme modification of porcine insulin (emp) or biosynthetically by recombinant DNA using bacteria (crb, prb) or yeast (pyr)
  • analogues

By duration of action

Rapid-acting insulin analogues5 mins1 hour3-5 hours
Short-acting insulin30 mins3 hours6-8 hours
Intermediate-acting insulin2 hours5-8 hours12-18 hours
Long-acting insulin analogues1-2 hoursFlat profileUp to 24 hours
Premixed preparations---

Patients often require a mixture of preparations (e.g. both short and long acting) to ensure stable glycaemic control throughout the day.

Rapid-acting insulin analogues
  • the rapid-acting human insulin analogues act faster and have a shorter duration of action than soluble insulin (see below)
  • may be used as the bolus dose in 'basal-bolus' regimes (rapid/short-acting 'bolus' insulin before meals with intermediate/long-acting 'basal' insulin once or twice daily)
  • insulin aspart: NovoRapid
  • insulin lispro: Humalog

Short-acting insulins
  • soluble insulin examples: Actrapid (human, pyr), Humulin S (human, prb)
  • may be used as the bolus dose in 'basal-bolus' regimes

Intermidate-acting insulins
  • isophane insulin
  • many patients use isophane insulin in a premixed formulation with