Insulin guide

The number of insulins available on the market is enormous and very confusing.   This page is to help you understand what insulins are used by the Leeds Children's Diabetes Team and how they work.  To help you understand how quickly your insulin works and for how long please refer to the chart below.

All insulin used by the Leeds Children's Diabetes Team is human insulin or derivatives of human insulin.  No animal based insulin is used.

Fast acting human insulin:

This works within 30 minutes and lasts between 7 to 8 hours. (Actrapid and Humulin S).

Long to medium acting human insulin:

These are modified to reach their peak action by 6 hours and wear off over20-24 hours. (Human Insulatard or Isophane).  These are rarely used on their own but as part of mixed insulin (Example Mixtard 30).

Rapid acting insulin analogue:

These are human insulins which have been modified slightly so that they are absorbed faster and therefore can be injected just before you eat. (Examples: NovoRapid and Humalog Lispro).

Premixed insulin:

Many of you will be on or have been on premixed insulin.  These are a mixture of fast acting insulin and long acting insulin.  Some premixed insulins are prescribed at different ratios of fast and long acting.  Therefore Mixtard 20 will be 20% fast acting and 80% long acting, Mixtard 30 will be 30% fast acting 70% long acting.   (Examples: Mixtard 10, 20, 30, 40, 50, M3).  Some premixed insulins are a mixture of rapid acting insulin analogue and long acting insulin (Examples: NovoMix 30, Humalog Mix 25).

Long acting insulin analogue:

These are human insulins that are modified to absorb very slowly and smoothly over 20-24 hours.  (Examples Glargine and Detemir).  These are used as part of multiple insulin injection regimens to provide background insulin and cause less hypoglycaemic episodes than the older long acting insulins.

To understand how they work look at the chart above.  For example you will see that NovoRapid starts to work very quickly, has its peak action from about 15 minutes to 180 minutes and finishes by 300 minutes.