They all come as injections containing 100 units of insulin per 1ml. Humalog and Lyumjev also come as injections containing 200 units of insulin per 1ml.

Everyone with type 1 diabetes, and some people with type 2 diabetes or gestational diabetes, needs to take insulin to help manage their blood glucose levels. This reduces the chances of getting the symptoms of high blood glucose (hyperglycaemia) and serious long-term problems that can damage the heart, kidneys, eyes, nerves and feet.

Unless you use an insulin pump, you'll usually take rapid-acting insulin along with another type of insulin called intermediate-acting insulin or long-acting insulin. This is taken once or twice a day and gives you the background insulin you need when you're not eating.

When your pancreas is working properly it makes small amounts of insulin all the time and releases more insulin when your blood glucose levels increase after eating. When you have diabetes, your body does not make enough insulin or the insulin it makes does not work properly.

Rapid-acting insulin is a type of very fast-acting insulin. This means it starts to work very quickly and you take it before meals to stop your blood glucose from going too high when you eat carbohydrates.

They come in different brands and are used with different types of insulin pen, but they all work in a similar way. Some brands work more quickly than others.

Insulin is a hormone made in your pancreas, which is a gland behind the stomach. It helps your body use glucose (sugar) for energy.