A guide to understanding different insulin types.

The discovery of insulin in 1922 was an important milestone in the treatment and management of diabetes. Insulin used was sourced from animals .Individuals with diabetes needed multiple daily injections, often needing to wake up in the middle of the night to inject. Allergic reactions were a common occurrence.

 Researchers and Scientists looked for ways that could address these challenges, leading to new methods of insulin production. This resulted in the introduction of synthetic human insulins in the 1980s, followed by analogue insulins in the 1990s. Synthetic insulins are man-made insulins that are identical to human insulin.

Analogue insulins are synthetic insulins whose structure has been changed to improve performance in the body. These alterations are done to improve absorption, resulting in rapid acting insulins or to delay absorption leading to long-acting insulins.

Types of insulins

Insulins are classified based on the time they take to begin working, time it takes to reach peak levels in the bloodstream, and the length of time they remain in the bloodstream.

Onset	Time it takes for the insulin to start working
Peak	Time it takes to reach maximum levels
Duration	How long it works to lower blood sugar

Rapid acting insulins

Example:  Novorapid, Apidra and Humalog

Onset	15 minutes
Peak	1- 2 hours
Duration	3-4 hours

Rapid-acting insulins are typically injected before meals or when a quick reduction in blood glucose levels is needed. They are often referred to as bolus insulins. When taken before meals they should be injected 15 minutes before a meal.

Short acting insulins

Example: Actrapid and Humulin R

Onset	30 minutes
Peak	2-3 hours
Duration	4-6 hours

Short acting insulins also known as bolus insulins are typically used before meals and should be injected 30 minutes before a meal.

Intermediate Insulins

Example: Protaphane and Humulin N

Onset	2 – 4 hours
Peak	8 hours
Duration	10 -16 hours

Intermediate insulins are often used as basal insulins. They provide insulin cover for approximately half a day and are normally used overnight.

 When your pancreas is functioning as it should it releases small amounts of insulin all the time to maintain blood glucose levels within range. Basal insulins provide this background insulin for individuals who have disturbances in their insulin production.

 They are often prescribed together with a short acting or rapid acting insulin.

Long-Acting Insulins

Example: Lantus and Toujeo

Onset	1-2 hours
Peak	Do not peak
Duration	24 hours

Long-acting insulins provide daily insulin coverage. They are often used as basal insulins ,and are prescribed alongside short or rapid-acting insulins.

Pre-mixed insulins

 Pre-mixed insulins are combination insulins often containing intermediate and short acting insulins. They can be categorized into pre-mixed human insulins and pre-mixed analogue insulins. The short acting component helps bring down glucose levels after a meal while the intermediate component provides those low levels of insulin needed throughout the day.

Pre-mixed human insulins

              Example: Actraphane and Humulin 30/70

Onset	30 minutes
Peak	Dual peak
Duration	10- 16 hours

The combination ratio for pre-mixed human insulins is 70/30, consisting of 70% intermediate and 30% short-acting insulin.

Pre-mixed analogue insulins

               Example: Novomix, Humalog mix and Ryzodeg

Onset	5- 15 minutes
Peak	Dual peak
Duration	24 hours

Common pre-mixed analogue insulins are combinations of rapid-acting insulin and intermediate-acting insulin. The ratio of these combinations can vary, with some preparations having 75/25, 50/50, and 70/30 ratios.

Analogue premixed insulins that contain rapid-acting insulins combined with long-acting or rapid-acting insulins are also available.

*Please be aware that the examples provided in this section do not cover all insulin preparations available in South Africa.