Insulin

What is insulin?

Insulin is a hormone that is made by beta cells in the pancreas. When you eat, insulin is released to stop the levels of glucose (sugar) in your blood going too high and becoming dangerous. It does this by moving glucose into your cells to give you energy.

Types of insulin for type 1 diabetes

There are different types of insulin that are used to treat type 1 diabetes. Most people with type 1 in the UK use two different insulins every day to manage the condition – slow-acting and fast-acting insulin. Combining these two insulins is often known as a ‘basal-bolus regime’ – you’ll see why further down.

Slow-acting insulin

Slow-acting insulin (also known as long-acting insulin) provides your body with the insulin it needs throughout the day and night. It’s also known as basal or background insulin because it mimics how the pancreas would usually release insulin steadily throughout the day. It’s usually injected in the morning and can last up to 24 hours.

Popular types of slow-acting insulin in the UK include:

• Insulin glargine (Lantus) – this takes effect after an hour and can last for 24 hours
• Insulin determir (Levemir) – this has a shorter effect than Lantus and so is often injected twice per day
• Insulin degludec (Tresiba) – this is often prescribed to reduce nocturnal hypoglycaemia in people over the age of 18

Fast-acting insulin

Fast-acting insulins (sometimes called rapid-acting or short-acting insulin) are usually taken just before you eat or drink something that has carbohydrates in it. This insulin minimises the rise in blood sugar after you eat or drink. It’s also known as bolus or mealtime insulin.

Types of rapid-acting insulin in the UK include:

• Insulin aspart (Novorapid) – takes effect approximately 10-20 minutes after injection
• Insulin aspart (Fiasp) – takes effect approximately 5 minutes after injection
• Insulin lispro (Humalog) – takes effect approximately 15-30 minutes after injection
• Insulin glulisine (Apidra) – takes effect approximately 10-20 minutes after injection

Basal-bolus regime

It’s called a basal-bolus regime because you combine the slow-acting basal and fast-acting bolus insulins every day.

One of the main advantages of a basal-bolus regime is that it mimics how the body would release insulin if you didn’t have type 1 diabetes – both steadily throughout the day and to bring down glucose levels after you’ve eaten.

The good thing about this is that it’s flexible because you can take bolus injections whenever you eat, but it usually means taking four to eight injections a day. Some people are fine with this but others might prefer to use an insulin pump.

Mix insulins

Some people choose to use a ‘mix’ insulin, where fast and slow-acting insulins are mixed together in a single dose. It’s good because it means you need fewer injections each day, but it reduces the flexibility you have throughout the day. People on mix insulins, such as Humalog Mix, usually have to eat fixed amounts of carbohydrates at fixed times and can find unplanned exercise especially difficult.

Getting insulin into your body

Injecting insulin

After you’re diagnosed with type 1, you usually start your treatment using multiple daily injections (MDI), using a combination of slow- and fast-acting insulin. 

Find out more about injecting insulin.

Insulin pumps

An insulin pump is a small device that delivers insulin throughout the day. It can relieve the burden of injecting insulin multiple times a day.

Find out more about insulin pumps.

Smart insulin pens

Smart pens are reusable insulin pens that send data to an app on your phone. The data records how much insulin you injected and when, helping you keep track of your daily injections. 

Find out more about smart insulin pens.