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About short-acting insulin - Brand names: Actrapid, Humulin S

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

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.

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.

Short-acting insulin (sometimes called regular insulin, soluble insulin or neutral insulin) starts to work quickly, and you take it before meals to stop your blood glucose from going too high when you eat carbohydrates.

Short-acting insulin is sometimes also known as bolus insulin or mealtime insulin.

Unless you use an insulin pump, you'll usually take short-acting insulin along with another type of insulin, called intermediate-acting insulin or long-acting insulin.

Short-acting insulin is available on prescription only. It comes as cartridges that you use in a reusable insulin pen and as a solution in a a small bottle (vial) for injecting or using in a pump.

Short-acting insulin brands and pens

There are 2 main brands of short-acting insulin. They both contain 100 units of insulin per 1ml of injection.

Actrapid comes in 10ml vials to use with a syringe.

Humulin S comes as:

  • 3ml cartridges to use in a reusable HumaPen Savvio insulin pen
  • 10ml vials to use with a syringe or in a pump

Key facts

  • Short-acting insulin starts to work after about 30 to 60 minutes and usually lasts up to 8 hours. You'll usually take it around 30 minutes before a meal.
  • Your doctor or diabetes nurse will tell you how much short-acting insulin to take. You may need to adjust your dose depending on the amount of carbohydrates in your meal (carb counting).
  • Insulin treats the symptoms of diabetes by lowering your blood glucose. But it can sometimes cause your blood glucose to go too low. This is known as hypoglycaemia, or hypos. Make sure you know the symptoms of a hypo, and always carry a source of glucose with you, such as sugary sweets, in case you need to treat a hypo.
  • It's a good idea to carry medical identification such as an insulin safety card or insulin passport – a small card with up-to-date details of the type of insulin you use, and what to do in an emergency.
  • If you have diabetes, you're entitled to free prescriptions for all your medicines, not just your insulin.

Page last reviewed: 7 July 2023
Next review due: 7 July 2026