Diabetes mellitus (diabetes) is a chronic and potentially life-threatening condition where the body loses its ability to produce insulin, or begins to produce or use insulin less efficiently, resulting in blood glucose levels that are too high (hyperglycaemia).
Excess glucose in the blood, over time, can damage your eyes, kidneys and nerves, and can also cause heart disease and stroke so it is important to reduce this risk.
An estimated 280 Australians develop diabetes every day. It is Australia's fastest-growing chronic disease. The main types of diabetes are type 1 and type 2 diabetes and also gestational diabetes. Gestational diabetes occurs during pregnancy and usually goes away after the baby is born.
Type 1 diabetes
Type 1 diabetes is life-threatening if not treated. It develops when the body's immune system sees its own cells as foreign and attacks and destroys them. As a result, the islet cells of the pancreas, which normally produce insulin, are destroyed. In the absence of insulin, glucose cannot enter the cell and glucose accumulates in the blood.Type 1 diabetes typically occurs in people under 30 years of age, but can occur at any age. It cannot be prevented or cured, at present. It is not linked to lifestyle factors. Its exact cause is not yet known but current research points towards something in the environment affecting people with a genetic risk. All people with type 1 diabetes need to inject insulin throughout their lives. Most people diagnosed with type 1 diabetes do not have family members with this condition (it is not an inherited condition). For more information including symptoms, visit the Diabetes Type 1 fact sheet.
Type 2 diabetes
Type 2 diabetes (once known as adult-onset diabetes) affects 85 to 90 per cent of all people with diabetes. It has a strong genetic link, but risk is greatly increased by lifestyle factors such as being overweight or obese and doing insufficient physical activity. People from certain ethnic backgrounds, such as Aboriginal or Torres Strait Islander, Polynesian, Asian or Indian are more likely to develop type 2 diabetes.
Type 2 diabetes occurs when the body cannot use insulin effectively. This is called insulin resistance and the result is the same as with type 1 diabetes – a build-up of glucose in the blood.
When first diagnosed, many people with type 2 diabetes can manage their condition with healthy diet and increased physical activity. Eventually most people with type 2 diabetes will need diabetes tablets to help keep their blood glucose levels on target. (Regular blood glucose monitoring may be necessary in order to keep track of the effectiveness of the treatment.) The starting time for diabetes tablets varies according to individual need. About 50 per cent of people with type 2 diabetes need insulin injections within 6 to 10 years of diagnosis.
For more information on Type 2 diabetes please visit the Diabetes Type 2 fact sheet.
Gestational diabetes is a form of diabetes that occurs in about 5 to 10 per cent of pregnancies and usually disappears after the birth of the baby. It significantly increases a woman's risk of developing type 2 diabetes in the future. Gestational diabetes is commonly managed by monitoring blood glucose levels, adopting a healthy eating plan and performing regular physical activity. Some women may need to inject insulin during their pregnancy to help manage their blood glucose levels until their baby is born.
Insulin for diabetes
Insulin is a hormone our body makes. It is made by beta cells in the pancreas. Insulin's main job is to move glucose from our bloodstream into the body's cells to make energy. It keeps our blood glucose levels within the normal range. If you have insufficient insulin, the glucose stays in your bloodstream, reducing the amount of energy made in your body.
With type 1 diabetes, the body does not make insulin and has to rely on insulin being injected regularly throughout the day to stay alive. With type 2 diabetes, the body does not make enough insulin, or the insulin that is made does not work well.
Starting on insulin
People with type 1 diabetes must inject insulin every day, often up to four or five times per day. Insulin cannot be taken by mouth because the stomach acid destroys it. Sometimes, people with type 2 diabetes also need to begin using insulin when diet, physical activity and tablets no longer effectively control their blood glucose levels.
Having to start injecting insulin can be frightening. However, injecting insulin is much easier than most people imagine. There are many devices which can be used to make injecting insulin easy and the needles are very fine. Often people who need to inject insulin feel much better once they start having insulin.
If you need to start using insulin, your doctor or diabetes nurse educator can help with education and support. They will teach you about:
- the type and action of your insulin
- how, where and when to inject insulin
- how to rotate injection sites
- where to get your insulin and how to store it safely
- how to keep a record of your blood glucose levels and insulin doses.
Your doctor or diabetes nurse educator will also help you to adjust your insulin dose according to your blood glucose levels. This means that blood glucose monitoring and recording is a necessary part of insulin adjustment.
It may take some time to safely reach the right dose of insulin for you, and remember that insulin doses don't always remain the same throughout your life. Therefore you will need to see your diabetes health care team regularly for review.
When you start using insulin it is important to have a review by an accredited practising dietitian to understand how carbohydrates and insulin work together.
Types of insulin
Insulin is grouped according to how long it works in the body. The five different types of insulin range from rapid- to long-acting. Some types of insulin look clear, while others are cloudy. Check with your pharmacist whether the insulin you are taking should be clear or cloudy.
Before injecting a cloudy insulin, the pen or vial needs to be gently rolled between your hands to make sure the insulin is evenly mixed (until it looks milky). Don't use clear insulin if it appears cloudy.
Often, people need both rapid- and longer-acting insulin. Everyone is different and needs different combinations.
The five types of insulin are:
- rapid-acting insulin
- short-acting insulin
- intermediate-acting insulin
- mixed insulin
- long-acting insulin.
Rapid-acting insulin starts working somewhere between 10 to 20 minutes after injection. Its action is at its greatest between one and three hours after injection and can last up to five hours. This type of insulin acts more quickly after a meal, similar to the body's natural insulin, reducing the risk of a hypoglycaemic attack (when blood glucose falls to below 4 mmol/L). When you use this type of insulin, you must eat immediately after you inject.
The three rapid-acting insulin types currently available in Australia are:
- NovoRapid (insulin aspart)
- Humalog (insulin lispro)
- Apidra (insulin glulisine).
Short-acting insulin takes longer to start working than the rapid-acting insulins.
Short-acting insulin begins to lower blood glucose levels within 30 minutes, so you need to have your injection 30 minutes before eating. It has its maximum effect two to five hours after injection and lasts for six to eight hours.
Short-acting insulins currently available in Australia are:
Intermediate-acting and long-acting insulins are often termed background or basal insulins.
The intermediate-acting insulins have protamine sulfate and zinc chloride added to delay their action and this is why they are cloudy in nature and need to be mixed well.
These insulins begin to work about 60 to 90 minutes after injection, peak between 4 to 12 hours and last for between 16 to 24 hours.
Intermediate-acting insulins currently available in Australia are:
- Humulin NPH (a human isophane insulin)
- Protaphane (a human isophane insulin).
The long-acting insulins currently available in Australia are:
- Lantus (glargine insulin) – slow, steady release of insulin with no apparent peak action. One injection can last up to 24 hours. It is usually given once a day but can also be given twice daily.
- Levemir (detemir insulin) – also slow, steady release of insulin with no apparent peak action and can last up to18 hours. It can be given once to twice daily.
Although these insulins are long-acting, they are clear and do not need mixing before injecting.
Mixed insulin contains a pre-mixed combination of either very rapid-acting or short-acting insulin, together with intermediate-acting insulin.
The mixed insulins currently available in Australia are:
- Rapid-acting and intermediate-acting insulin
- NovoMix 30 (30% rapid, 70% intermediate Protaphane)
- Humalog Mix 25 (25% rapid, 75% intermediate Humulin NPH)
- Humalog Mix 50 (50% rapid, 50% intermediate Humulin NPH)
- Short-acting and intermediate-acting insulin
- Mixtard 30/70 (30% short, 70% intermediate Protaphane)
- Mixtard 50/50 (50% short, 50% intermediate Protaphane)
- Humulin 30/70 (30% short, 70% intermediate Humulin NPH)
In Australia the strength of the above insulins are 100 units per mL. Some other countries have different strengths.
A new, longer-acting insulin released in Australia in July 2015 is Toujeo (insulin glargine, 300 units per mL). This is a more concentrated form insulin glargine 100 units per mL. It is important not to change between them without consulting a health professional. Toujeo is once-daily basal insulin.
Insulin injection devices
Many different insulin injection devices are available. The main choices are syringes, insulin pens and insulin pumps.
Syringes are manufactured in 30 unit (0.3 ml), 50 unit (0.5 ml) and 100 unit (1.0 ml) measures. The size of the syringe needed will depend on the insulin dose. For example, it is easier to measure a 10 unit dose in a 30 unit syringe and 55 units in a 100 unit syringe.
The needles on the syringes are available in lengths ranging from 8 mm to 13 mm. Your doctor or diabetes nurse educator will help you decide which syringe and needle size is right for you.
Insulin syringes are single-use only, and are free for people in Australia registered with the National Diabetes Service Scheme (NDSS). Note that most Australian adults no longer use syringes to inject insulin. They now use insulin pens for greater convenience.
Insulin companies have designed insulin pens (disposable or reusable) to be used with their own brand of insulin. Disposable devices are pre-filled with insulin and discarded when they are empty, when they have been out of the fridge for one month, or when the use-by date is reached.
Reusable devices require insertion of an insulin cartridge or 'penfill' (3 ml, containing 300 units of insulin). When finished, a new cartridge or penfill is inserted.
Your doctor or diabetes nurse educator will advise you about the right type of pen for your needs.
Pen needles are disposable needles that screw on to the insulin pen devices to allow insulin to be injected. They are available in different lengths, ranging from 4 mm to 12.7 mm. The thickness (gauge) also varies – the higher the gauge, the finer the needle. It is important that a new pen needle is used with each injection. Your diabetes nurse educator can advise you on the appropriate needle length and show you correct injection technique
An insulin pump is a small programmable device that holds a reservoir of insulin and is worn outside the body. It is programmed to deliver insulin into the body through thin plastic tubing known as an infusion set or giving set. Only rapid-acting insulin is used in the pump.
The infusion set has a fine needle or flexible cannula that is inserted just below the skin (usually on the abdomen). This is changed every two to three days.
The pump is pre-programmed to automatically deliver small continual amounts of insulin to keep blood glucose levels stable between meals. Individuals can program the pump to deliver a burst of insulin each time food is eaten, similar to the way the pancreas does in people without diabetes.
The insulin pump isn't suitable for everyone. If you're considering using one, you must discuss it first with your diabetes healthcare team.
The cost of an insulin pump is generally covered by private health insurance for people with type 1 diabetes (a waiting period applies). Disposable extras required for use (such as cannulas, lines and reservoirs) are subsidised by the National Diabetes Service Scheme.
Insulin injection sites
Insulin is injected through the skin into the fatty tissue known as the subcutaneous layer. It shouldn't go into muscle or directly into the blood, as this changes the speed of absorption.
Absorption of insulin varies depending on where in the body it is injected. The abdomen absorbs insulin the fastest and is used by most people. The upper arms, buttocks and thighs have a slower absorption rate and can also be used.
Factors that speed insulin absorption
Variation in insulin absorption can cause changes in blood glucose levels. Insulin absorption is increased by:
- injecting into an exercised area such as the thighs or arms
- high temperatures due to a hot shower, bath, hot water bottle, spa or sauna
- massaging the area around the injection site
- injecting into muscle – the deeper the injection into muscle, the faster the insulin will be absorbed.
Factors that delay insulin absorption
Insulin absorption can be delayed by:
- cigarette smoking
- over-use of the same injection site, which causes the area under the skin to become lumpy or scarred (known as hyperlipotrophy)
- insulin that is cold (for example, if insulin is injected immediately after taking it from the fridge).
Disposal of used insulin syringes
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 containers are usually yellow and are available through pharmacies, local municipal councils and State or Territory diabetes organisations such as Diabetes Victoria.
Procedures to dispose of sharps containers vary from state to state.
For sharps disposal information and help, you can contact:
- state or territory diabetes organisations, such as Diabetes Victoria
- state department of health
- your local municipal council.
Insulin requires some care in storage to ensure its effectiveness. This includes:
- storing unopened insulin on its side in a fridge
- keeping the fridge temperature between 2 – 8°C
- making sure that insulin does not freeze
- once opened, keeping it at room temperature (less than 25 °C) for one month and then disposing of it safely
- avoiding keeping insulin in direct sunlight.
Extreme (hot or cold) temperatures can damage insulin so it doesn't work properly. It must not be left where temperatures are over 30 °C. In summer your car can get this hot (above 30°C) so don't leave your insulin there.
There are various insulated insulin carry bags (such as FRIO) available for transporting insulin.
Don't use insulin if:
- clear insulin has turned cloudy
- cloudy insulin has lumps or flakes suspended in it, or deposits of insulin are visible on the inside of the vial, penfill or cartridge and cannot be dissolved by gentle rotation
- expiry date has been reached
- it has been frozen or exposed to high temperatures
- a vial, penfill or cartridge has been used or has been out of the fridge for longer than one month.
Record your blood glucose levels and insulin doses
Keeping a written record of your blood glucose levels helps you and your healthcare professional to know when your insulin dosage needs adjustment.
Where to get help
- Your doctor
- Diabetes nurse educator
- Local community health service
- Diabetes Australia Infoline Tel. 1300 136 588
Baker IDI Heart and Diabetes Institute Tel. (03) 8532 1111
Things to remember
- People with type 1 diabetes must inject insulin every day, often up to four or five times per day.
- There are many devices which can be used to make injecting insulin easy and the needles are very fine.
- Your doctor or diabetes nurse educator will teach you about how, where and when to inject insulin, and how to store it safely.
- Even with the help of your doctor and diabetes nurse educator, it may take a while to find the right insulin dose to reduce your blood glucose to your target levels.