Rapid-acting Insulin

Common Brand Names

There are 3 different types of rapid-acting insulin:

• Insulin Aspart (Fiasp, NovoRapid and Trurapi)
• Insulin Glulisine (Apidra)
• insulin Lispro (Admelog, Humalog and Lyumjev)

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.

Rapid-acting insulins usually come in a strength of 100 units per 1ml, but some, like Humalog and Lyumjev, are also available in a higher concentration of 200 units per 1ml. 

Rapid-acting insulin comes as:

• pre-filled pens
• cartridges that you use in a reusable insulin pen
• cartridges that you use in an insulin pump
• a solution in a vial (a small bottle) for injecting or using in a pump

It’s important to always check the strength of your insulin before using it. Using the wrong strength can cause problems, like taking too much (overdosing) or too little (underdosing) insulin.

Overview

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.

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.

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

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.

Important Facts

• Rapid-acting insulin starts to work after about 10 to 20 minutes and lasts for up to 5 hours. You'll usually take it around 15 minutes before a meal but it can be taken up to 10 minutes after a meal.
• Your doctor or diabetes nurse will tell you how much rapid-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.
• If available in your country, 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.

Your dosage

Rapid-acting insulin usually contains 100 units of insulin per 1ml of liquid, but some brands are also available containing 200 units of insulin per 1ml of liquid. Make sure you know what strength of insulin you're taking.

You'll usually take a dose of rapid acting insulin around 10 to 15 minutes before each meal. Your doctor or diabetes nurse will advise you on when to take it. The exact timing may depend on which brand you take. See what timing works best for you and try to stick to it as closely as possible.

Taking it before meals means that your levels of insulin are highest as your body absorbs glucose from the meal, which helps to stop your glucose level from going too high.

Your doctor or diabetes nurse will tell you how many units of insulin you'll need to take. You'll usually need to calculate your dose depending on the amount of carbohydrate food (sugar and starches) in each meal. This is known as carb counting. If you have type 1 diabetes you should be given training in how to do this.

The dose of rapid-acting insulin you need also depends on:

• your weight
• the type of diabetes you have
• how active you are
• whether you're taking other medicines for diabetes

Changes to your dose

As well as adjusting your dose for what you eat, you may also need to change your dose:

• when you're ill
• if you're stressed
• in hot or cold weather
• if you're doing exercise
• when you start or stop some medicines
• during the menopause
• if you're pregnant
• while you're growing if you're a child or young person
• if you're fasting (for example during Ramadan or for other religious reasons)
• if you change your daily routine, for example if you're doing shift work

It's a good idea to keep a record of the amount of insulin units you inject if possible.

If you’re ever unsure about your dose, you should talk to your doctor or diabetes care team for advice.

Testing your blood glucose

Testing your blood glucose regularly will help you and your diabetes healthcare team know if you're taking the right dose for you. Your doctor or diabetes nurse should explain how to do this.

 How To Use Insulin Pens

Most people take rapid-acting insulin using an insulin pen or a pump. The type of pen you'll use depends on which brand of insulin you've been prescribed. There are different types of pre-filled pens, reusable pens and pumps so check the instructions for the type you're using.

If you use vials and syringes to inject instead of a pen, your diabetes nurse should show you how to do this.

Some people use an insulin pump instead of a pen. This is a device you attach to your body that gives you small amounts of insulin throughout the day and night.

When you're first prescribed insulin you should be shown how to use your pen or your pump.

Using an Insulin Pen

When you start taking insulin your diabetes nurse or doctor should show you how to use your pen to inject. Always follow the specific instructions provided for your pen. 

Using an insulin pen does not usually hurt. The needles are very small as you only inject a small amount into the layer of fat just under your skin.

The guide below is for general information only and may not apply to your specific pen or treatment.

1. Wash your hands.
2. Attach a new needle to your pen every time you inject.
3. Remove any air from your pen by turning the dial to 2 units of insulin, pointing the pen up into the air and pressing the plunger until insulin starts to come out of the needle. If no insulin comes out then do this again.
4. Dial your dose of insulin by turning the dial on the pen to the correct number.
5. Choose a place to inject on your tummy, the sides of your thighs or your buttocks – make sure you use a different place each time.
6. Hold the pen at a right angle to your skin and push the needle into your skin.
7. Push the plunger in slowly, then hold the pen in place for 10 seconds to make sure you get the full dose.
8. Take the pen out of your skin, remove the used needle and put it in your sharps bin, then put the cap back on your pen.

It's important to vary the places you inject so that you're less likely to get fatty lumps under your skin (lipohypertrophy). Although these are usually harmless, they can mean that insulin is not always absorbed at the same speed when you inject into them. This can affect your blood glucose levels.

If You Forget To Take Your Insulin

Taking too little insulin can lead to high blood sugar (hyperglycaemia) and increase the risk of long-term complications from diabetes. It’s important to take your insulin as prescribed, but if you forget a dose, here’s what you can do:

• If you forget to take your rapid-acting insulin before a meal, and you've already eaten, consider taking a slightly smaller dose or correction dose, or contact your doctor or diabetes nurse for advice.
• Look out for any signs of high or low blood glucose levels, and check your blood glucose levels more often than usual. Contact your doctor or diabetes nurse if you're concerned.
• Never take 2 doses to make up for a forgotten dose.

Too Much Insulin and Low Blood Sugar

Taking too much insulin can make your blood sugar go too low, causing hypoglycaemia (a hypo). You might also have a hypo if you:

• miss or delay meals or have not had enough carbohydrates
• do lots of exercise without having the right amount of carbohydrates or reducing your insulin dose
• drink alcohol, especially after skipping a meal

Symptoms Of a Hypo:

Symptoms of low blood sugar include:

• sweating
• trembling or shaking
• anxiety, confusion or difficulty concentrating
• fast heartbeat (palpitations)
• tingling lips
• changes to your vision such as blurred vision
• feeling dizzy
• feeling hungry
• paler than usual skin

At Night: It's also possible for your blood sugar to go too low while you're asleep. If this happens, you may wake up at night feeling sweaty and confused, or you may feel tired or have a headache in the morning. Speak to your diabetes team if you think you might be having hypos at night.

These symptoms happen when your blood glucose falls below 4mmol/L.

Treating a Hypo

If you get hypo symptoms, follow the instructions you've been given to treat a hypo:

1. Have a sugary drink or snack, such as a small glass of fruit juice or sugary fizzy drink, 5 glucose or dextrose tablets, 4 large jelly babies, or 2 tubes of glucose gel.
2. Check your blood glucose after 10 to 15 minutes. If it's improved and you feel better, move on to step 3. If it's still low, have another sugary drink or snack, then check your blood glucose again after 10 minutes.
3. Once you blood glucose is back above 4mmol/L, eat a starchy carbohydrate that lasts longer in your blood, like a sandwich or some biscuits, or your next meal if it's due.
4. Once you feel better and your blood glucose is back under control, you can restart your insulin treatment

Tip: Always carry glucose tablets or high sugar snacks with you in case you have a hypo.

Important Safety Tips

• Do not drive, cycle or use machinery if you've taken too much insulin, even if you do not have symptoms. If you have a hypo, do not drive for at least 45 minutes after you've recovered.
• Try to make sure someone stays with you if you've taken too much insulin.
• If you have very low blood glucose (a severe hypo) you may become drowsy or unconscious. Make sure your family or friends know what to do if this happens, including how to give a glucagon injection, and when to call for an ambulance.

Storing and Travelling with Insulin

Storing Insulin At Home

At Home:

• Keep your disposable insulin pens or cartridges in the fridge until you start using them. 
• Keep them away from the freezer section or cooler element inside the fridge. If the insulin freezes you'll need to throw it away.

Always Have a Spare

• Always try to have at least one spare pen or cartridge available in case your current one is damaged, lost, or runs out unexpectedly. This ensures you never miss a dose, which is important for keeping your blood sugar under control.

Insulin that you're using

Using Insulin at Room Temperature:

• Once you start using a new disposable pen or cartridge, you can keep it out of the fridge at room temperature for up to 4 weeks.
  
• Injecting cold insulin straight from the fridge can be painful, so it's best to let it warm up to room temperature before you use it.

Avoid Heat:

• Keep your insulin pen out of direct sunlight and away from radiators. If it gets too warm the insulin may not work properly.
• Rapid-acting insulin that has been kept out of the fridge for longer than 28 days may not work properly, so you'll need to return it to your pharmacy to dispose of it. You can write the date that you took it out of the fridge on the packaging, to help you remember.
  

Travelling with insulin

Taking insulin will not stop you from travelling, but it's important to plan ahead.

If you're away from home, it's a good idea to take an extra supply of insulin with you.

If necessary, keep it in a cool bag while travelling, but be careful not to put it next to an ice block so that it does not freeze.

If you're going on holiday:

• pack extra medicine – speak to your diabetes nurse or pharmacist about how much to take if you're unsure
• find out how you can get insulin in the place you're visiting, and take a recent prescription with you
• carry your insulin in your hand luggage if you're flying
• take a letter from your doctor or diabetes care team to say you have diabetes and need to take your insulin and your equipment such as insulin pens and needles onto the plane (you may need to pay for the letter)
• let the airline know well in advance if you use an insulin pump or a glucose monitor (a sensor that you wear attached to your body to check your blood glucose)
• if you'll be crossing several time zones, ask your doctor or diabetes nurse how to adjust your insulin doses