Insulin is a hormone naturally produced in the body by the beta cells of the pancreas. Insulin allows glucose to enter the body's cells where it is used for energy. It also allows excess glucose to be stored in the liver for later use, such as overnight and between meals. A small amount of insulin is released from the pancreas into the bloodstream throughout the day and when food is eaten.
Insulin was first manufactured by scientists in 1922, and since then insulin therapy has been a revolutionary and lifesaving treatment for people with type 1 diabetes and is necessary to achieve target blood glucose levels in many people with type 2 diabetes.
Originally insulin was extracted from the pancreas of pigs and cows, but is now manufactured by genetic engineering to be similar to human insulin. New insulins, called analogues, have been created which act more quickly or slowly in the body than regular insulin. In this 'Expert Update' clip, Cath Prochillo, Diabetes Educator at Diabetes Victoria, discusses the insulin needs of people with type 1 diabetes.
To view more clips from Cath and other diabetes experts, download one of the free RealTime Health type 1 diabetes apps:
Why do people with type 1 diabetes need insulin?
People with type 1 diabetes no longer produce insulin and therefore need to take injections of insulin several times each day, every day. Prior to the discovery of insulin, and in countries where insulin is unavailable or unaffordable, it is a fatal condition. With modern insulins and diabetes care, people with type 1 diabetes can live a long and healthy life.
How is insulin taken?
Insulin cannot be taken by mouth as it is destroyed by the digestive chemicals in the stomach. Other forms of insulin therapy have been trialled, such as, inhaled or transdermal patch (through the skin) however, to date injections remain the most reliable, effective and inexpensive way of administering insulin. With modern technology, injecting insulin has become easier and almost painless with a greater choice of devices.
Insulin pens make injecting simpler and more convenient. Reusable insulin pens are used with 3ml insulin cartridges. Each cartridge contains 300 units of insulin. Insulin pens are made to fit specific brands of insulin. They are not interchangeable. Disposable insulin pen devices are prefilled with 300 units of insulin and discarded when empty. Pen needles can be used with any brand of pen and come in several different lengths to make injections as painless as possible.
New ADEA clinical recommendations suggest that most people who need to inject insulin can use shorter length needles such as 4, 5 and 6mm regardless of age or weight. These shorter needles may also be appropriate for people who are currently using 8 or 12mm pen needles. Your diabetes educator will help you to select the appropriate length pen needle for your injections and can advise you if the new clinical recommendations are appropriate for your situation.
Insulin pens available in Australia
|Reusable pens||Disposable pens||Insulin brand|
|NovoPen 4||FlexPen||Novo Nordisk insulins|
|NovoPen 3 Demi||InnoLet|
|HumaPen Luxura||KwikPen||Lilly insulins|
|HumaPen Luxura HD|
|ClikSTAR||SoloStar||Sanofi Aventis Insulin|
Syringes may be used if two types of insulin need to be mixed in special amounts. Syringes come in 0.3 ml (30 units), 0.5 ml (50 units) and 1ml (100 units) sizes. Syringes and needles are made to be used only once and then discarded.
Insulin pumps are battery operated devices that deliver a continuous small dose of insulin with extra insulin given with meals. Find out more about insulin pumps.
Ask your diabetes educator about the injection device that is best for you.
National Diabetes Services Scheme
Needles and syringes are free for people registered with the National Diabetes Services Scheme (NDSS). If you have a current Medicare card a doctor or 'credentialed' diabetes educator can register you on this scheme. Insulin pump lines are subsidised by the NDSS for eligible registrants. Contact Diabetes Victoria for more information or to obtain a NDSS registration form.
Types of insulin
The number of injections required and the type and dose of insulin varies between individuals and should be tailored to your lifestyle and eating habits and will be decided on the basis of your blood glucose pattern throughout the day and before and after meals. For optimal blood glucose levels, quick acting insulin delivered by an insulin pump or long acting insulin (basal insulin) once or twice daily, plus quick acting insulin with meals (bolus insulin) is the usual regimen for people with type 1 diabetes.
Are there any side effects to insulin?
Insulin is very safe when used with the guidance of your health professional and at the correct dose. The main side effect is hypoglycaemia (low blood glucose level). Mild hypoglycaemia can be treated very quickly by the person with diabetes without too much disruption to their day. Very low blood glucose levels can be dangerous and must not be ignored. Find out more about hypoglycaemia. Some people may experience a slight reaction where the injection was given. This usually goes away within a few days. Very rarely, a person may experience a reaction to the insulin that requires them to stop it and start another type of insulin. If you experience any side effects please inform your doctor. Controlling weight gain can be an issue after starting insulin therapy. This can be helped by increasing exercise and avoiding eating excess food and preventing hypos. Frequent hypos can be a cause of weight gain.
Insulin is injected through the skin into the fatty tissue known as the subcutaneous layer. Fatty lumps can develop in places that are over-used for injecting insulin so it is important to inject in a different spot each day. Insulin does not work as effectively when injected into areas of lipohypertrophy. If you do have lipohypertrophy, the lumps can go away if you avoid injecting in these areas for a while. However, it may work better in a new site and cause hypoglycaemia so discuss this with your doctor or diabetes educator as your insulin may need to be reduced.
1. Abdomen (tummy)
2. Upper outer arms (not into muscle)
4. Upper outer thighs
The abdomen is the preferred site as the absorption of insulin is more stable and most people have some fat under the skin here. You should avoid injecting into a muscle because it will be absorbed more quickly and could cause hypoglycaemia. Subcutaneous Injection Guidelines suggest that shorter length needles 4, 5 and 6mm are generally recommended for both children/adolescents and adults including obese patients when using pen needles. Your diabetes educator will help you to select the correct pen or syringe needle length, angle of injection and if you are required to pinch up the skin when injecting.
Source: Diabetes Australia information sheet "Insulin & Diabetes" (no.24) & ADEA Clinical Recommendations 'Subcutaneous Injection Technique for Insulin and Glucagon-like Peptide 1'
Storage of insulin
- Unopened insulin should be stored in the fridge, between 2-8 degrees Celsius. Once opened, insulin may be kept at room temperature (below 25-30 degrees Celsius) for one month and then discarded.
- Insulin can be damaged by extreme temperatures. It must not be left where temperatures reach over 30 degrees, eg. in the car or in direct sunlight.
- Insulin should not be allowed to freeze as it will lose its potency, and must be discarded. Find out more information about storage of insulin when travelling or camping.
Discard insulin when
- Clear insulin has turned cloudy
- The expiry date has been reached
- The insulin has frozen or has been exposed to high temperatures
- Lumps or flakes are seen in the insulin
- Deposits of insulin are seen on the inside of the vial and cannot be dissolved by gently rotating the vial
- The vial has been open for longer than one month (regardless of whether it has been in the fridge or expiry date has not been reached).
When you start insulin
People with diabetes need to learn to self manage their diabetes, and to do this well takes time, education and support. When you start insulin, you should have the help of a diabetes nurse educator who will teach you:
- How to inject insulin and how it works
- How to check your blood glucose levels (BGL)
- How to adjust insulin doses when you play sport or travel
- How to count carbohydrates and match your insulin to the food you eat. Find out more, go to DAFNE
- What to do if BGL are high or low
- How to recognise and treat a 'hypo' (low blood glucose)
- What to do when you are sick
- Where to get the equipment you need
- How to join the National Diabetes Services Scheme (NDSS)
Used syringes, pen needles and lancets must be disposed of in an Australian Safety Standards-approved sharps container which is puncture proof and has a secure lid. These are usually yellow in colour and are available through pharmacies, your local municipal council and Diabetes Victoria. Have a read of our Sharps disposal information sheet for more details.
Insulin for Life
People in many developing countries are unable to access insulin and strips, which affects their health and survival. If you have no longer needed, unopened and in-date (with at least three months to use-by date) insulin and test strips, please consider donating them to "Insulin for Life Inc." or at PO Box 2010 Ballarat Mail Centre, Vic 3354. These are then donated overseas following specific requests from recognised organisations and with an agreed protocol. Visit there website for more information.