What is type 1 diabetes? 

Type 1 diabetes is a long-term disease that affects the ability of your body to control the level of glucose (sugar) in the blood. If it is not properly managed, it can lead to serious health problems. It is an autoimmune condition in which the body produces little or no insulin. It is different to type 2 diabetes, which can be caused by multiple factors, such as obesity.

There are around 120,000 people in Australia with type 1 diabetes,1 with most having developed it in childhood or early adulthood. Girls and boys are affected at about the same rate. Australia has very high rates of type 1 diabetes, but it is not clear why this is the case.


In type 1 diabetes, an autoimmune reaction damages the cells in the pancreas that produce insulin, called beta cells. The exact reasons for this autoimmune targeting of beta cells is not known. Without beta cells, insulin cannot be produced to regulate glucose concentrations in the blood. This means that glucose can no longer enter cells in the body and instead accumulates in the bloodstream (a condition called hyperglycaemia).

Glucose and insulin

Glucose is an essential energy source for the body's cells. Food containing carbohydrates is broken down into glucose that travels around the body in the blood, to be absorbed by cells that use it as an energy source. Insulin works to help glucose pass into the cells.

For the body to be healthy, blood glucose needs to stay within a certain range. If it does not, this can lead to serious health problems, both in the short-term and over time.

Diagram of the digestive system showing how a reduced amount of insulin produced by the pancreas prevents glucose from food enter the tissues of the body.

Type 1 diabetes results in reduced insulin production, which causes an increase in blood glucose levels.

A less common form of type 1 diabetes is called latent autoimmune diabetes in adults (LADA). This form of diabetes also affects production of insulin, but the damage to the pancreas occurs much more slowly. A person with LADA is initially capable of producing insulin, but this changes over time, such that they will usually require insulin treatment. This change occurs more slowly than classic type 1 diabetes, but faster than with type 2 diabetes.

Risk factors

The risk factors for developing type 1 diabetes are not completely understood. Having a family member with type 1 diabetes slightly increases the risk of developing the condition. Other factors that may affect risk include:

  • Environmental factors – the risk increases the further you live away from the equator;
  • Exposure to some viruses, such as mumps and the virus that causes mononucleosis, increases the risk, and;
  • Early diet – babies who are introduced to cow's milk and certain other food substances early are at increased risk. Breastfed babies may be at a lower risk. 

Signs and symptoms

The severity of symptoms can vary with type 1 diabetes, with some people becoming very ill while others may have few symptoms or none at all. 

Classic symptoms include:

  • Increased thirst; 
  • Increased hunger;
  • Increased frequency of urination, which can manifest as urinating more frequently at night or bedwetting, and;
  • Unexpected weight loss.

Occasionally, individuals may not recognise these symptoms, and only get diagnosed after they become very unwell with an immediate complication, such as low blood glucose (hypoglycaemia) or diabetic ketoacidosis (see below). 

Methods for diagnosis

If type 1 diabetes is suspected, your doctor may recommend the following blood tests:

Random plasma glucose test

This test can be performed without the need to fast. It is used when there are significant symptoms. A test result of 11.1 mmol/L or greater suggests diabetes.

Fasting plasma glucose test

This test is performed on a blood sample taken after an overnight fast. Fasting is when no food or drinks (except water) are consumed prior to the sample being taken. A test result of 7.0 mmol/L or greater can confirm the diagnosis.

Glycated haemoglobin test

The glycated haemoglobin (HbA1C) test represents the average blood glucose levels over the past three months. A test result of greater than 6.5% can support the diagnosis of type 1 diabetes.

Oral glucose tolerance test 

The oral glucose tolerance test (OGTT) is currently the most reliable way to diagnose uncertain cases of diabetes. In this test, you need to fast overnight and then have a blood test to measure the level of glucose in the blood. This gives a baseline-level blood glucose. You then consume a drink containing 75g of glucose and after one and two hours, further blood tests are taken. A test result of 11.1 mmol/L or greater at two hours is used to define diabetes.

Antibody and ketone testing

Auto-antibodies are proteins produced by your immune system that target their own organs. In the case of type 1 diabetes, the antibodies target the insulin-producing cells in the pancreas. These specific antibodies can be detected by a blood test.

It is possible to test for ketones in the urine and blood. Ketones are a waste product from the breakdown of fat that occurs with ketoacidosis. Their presence may indicate type 1 diabetes.

Types of treatment

The key to treatment is supplementing the body's requirement for insulin and keeping the level of glucose in the blood within a healthy range. It is a lifelong condition that requires daily care to prevent serious complications. You will often have numerous health professionals to regularly review and help guide your treatment. However, you will need to have an active role in your care for the best outcomes. 

Treatment is tailored to each person's needs and includes a combination of insulin injections and:

  • Careful self-testing of blood glucose levels;
  • Blood pressure and cholesterol control;
  • Education about how to look after yourself;
  • Meal planning and weight control;
  • Regular physical activity;
  • Foot care, and;
  • Eye care.


Insulin is administered by an injection under the skin, as it cannot be taken as a tablet. Alternatively, it can be given by an insulin pump, which is a programmable device that delivers insulin via fine tubing into the skin and can stay in place for 2-3 days at a time.

A diagram showing an insulin pump worn on the back at the hip and how insulin is delivered by a catheter into the skin.

A portable pump may be used to deliver insulin into the fat layer below the skin.

There are many different types of insulin that have different periods of activity including:

  • Rapid-acting insulin, which starts working in 5-15 minutes and peaks 30-90 minutes after injecting;
  • Short-acting insulin, which starts working 30-60 minutes after injection and generally peaks in 2-4 hours;
  • Intermediate-acting insulin, which starts working 1-3 hours after it is taken and peaks in eight hours, and;
  • Long-acting insulin, which can provide coverage for as long as 20-26 hours.

Your doctor will advise you on the amount and type of insulin to take, and at what time. Administering too much insulin may result in low glucose levels (hypoglycaemia), and not enough can cause high levels. The requirement for insulin can change over time, depending on numerous factors including diet, physical activity and illness. With time you will learn how to self-adjust your insulin dose to meet your body's requirements. Your doctor or nurse can always help with these adjustments when needed.     

When you are first diagnosed with type 1 diabetes, you will be taught how to self-administer insulin and/or set up an insulin pump. Insulin needs to be carefully stored in a cool place, such as the fridge, for it to be effective. Your nurse or pharmacist can provide you with all the necessary training and equipment to help manage your insulin. 


With type 1 diabetes, you need to regularly check your blood glucose levels, maybe up to six times a day. Regular checking helps to identify extremes in blood glucose levels, and to calculate the amount of insulin needed. There are many portable devices available to test blood glucose levels. They all rely on using a sample of blood taken from a finger prick to rapidly provide a reading. You will often be taught how to use a self-testing blood glucose device when you are first diagnosed with diabetes. These devices need to be carefully maintained for them to be accurate. Your doctor, nurse or pharmacist can provide all the necessary information on these devices.  


In type 1 diabetes, maintaining a healthy lifestyle is an important part of managing blood glucose levels.

Healthy diet  

A well-balanced, healthy diet can help to manage blood glucose levels. A low-fat diet with plenty of fruits, vegetables and wholegrains is recommended. Meals and snacks – particularly the amount and type of carbohydrates they contain – need to be coordinated with the insulin dose to keep blood glucose levels steady. If you need help planning your meals, a dietitian can provide guidance.

Physical activity

Regular physical activity is beneficial for general health and an important part of controlling blood glucose levels. However, if blood glucose levels are poorly controlled, it can cause problems. It is important to talk to your doctor about what activities are suitable, situations when you should avoid exertion and any precautions you may need to take in order to be active safely. 


Maintaining a healthy weight is an important part of managing type 1 diabetes. Carrying extra weight or being obese can increase the risk of developing serious long-term complications.

Quit smoking

Smoking significantly increases the risk of complications occurring with type 1 diabetes. If you smoke, your doctor can provide guidance and help with quitting.

Potential complications

Short-term complications

Short-term complications with type 1 diabetes can develop very quickly and require rapid management or medical treatment. 


Hypoglycaemia is a condition in which the level of glucose in the blood falls too low. It can happen to people taking certain medication for diabetes, particularly if they delay or miss a meal, drink alcohol or are more physically active than usual.

If blood glucose levels fall too low, symptoms can include:

  • Feeling weak, light-headed or dizzy;
  • Trembling and shaking;
  • Feeling hungry;
  • Sweating;
  • Difficulty concentrating;
  • Feeling irritable or teary, and;
  • Numbness around the fingers or lips.

Severe hypoglycaemia is a serious condition that can cause a loss of consciousness. Monitoring blood glucose levels and taking steps to raise them if they begin to drop can help to prevent hypoglycaemia.   

A glucagon injection can be administered to help rapidly increase levels of blood glucose in severe cases of hypoglycaemia, when a person loses consciousness or is no longer able to swallow. Kits are available for people with type 1 diabetes to carry with them. However, because glucagon is usually only used in severe cases, it is very helpful for family, close friends, teachers and workmates to be educated on how to give the glucagon injection.

Diabetic ketoacidosis

Without insulin, the cells cannot absorb glucose, so the body uses stores of fat instead. This process produces a build-up of waste products in the blood that can cause a life-threatening condition called diabetic ketoacidosis. The signs of this condition include dehydration, vomiting, abdominal pain, headache, confusion, drowsiness, trouble breathing and a fruity smell to the breath that has also been compared to the smell of nail polish. Diabetic ketoacidosis requires emergency treatment.

Long-term complications

Having high blood glucose levels for an extended period of time can cause damage in many parts of the body and lead to serious health problems. Effective management of type 1 diabetes can help to prevent these conditions and minimise their effect on your health.

Male body showing organs and tissues that can be damaged by type 2 diabetes.

Potential long-term complications of type 1 diabetes.

Heart disease

Type 1 diabetes increases the risk of heart disease because a high level of glucose in the blood can directly damage the structure and function of the heart and its blood supply. This can result in high blood pressure, which causes your heart to work much harder to pump blood around your body and can lead to development of a condition known as hypertension. Atherosclerosis can occur when arteries are damaged and become clogged with plaques of fats and other products. Untreated, atherosclerosis and high blood pressure significantly increase the risk of heart attack, stroke and kidney damage.

Nerve damage

Nerve damage, also known as neuropathy, is common in the lower legs of people who have had diabetes for a long time, particularly if blood glucose levels have not been controlled well.

There are two main types of neuropathy: peripheral and autonomic. The most common in diabetes is peripheral neuropathy. Symptoms can include tingling, numbness, discomfort and pain that usually begins at the tips of the toes or fingers and steadily moves up the limbs.

Autonomic neuropathy can affect many parts of your body causing dizziness, fainting, urinary problems, excessive sweating, nausea or vomiting and diarrhoea or constipation

Kidney damage

Kidney damage, also known nephropathy, occurs when blood vessels that form part of each kidney are damaged by high blood glucose levels over time. These blood vessels filter waste out of the blood so it can be removed from the body. Nephropathy prevents normal kidney function.

In the long-term, damage can lead to the kidneys failing or irreversible end-stage kidney disease. In this case, dialysis or a kidney transplant will be required.

Eye conditions

Type 1 diabetes can damage blood vessels in the retina leading to a condition called diabetic retinopathy, which can potentially lead to vision loss or blindness. Type 1 diabetes also increases the risk of other serious eye conditions such as glaucoma and cataracts.

People with type 1 diabetes are recommended to have an eye examination at least once every two years. 

Foot problems

Nerve and blood vessel damage may lead to ulcers and serious foot problems that are difficult to treat. The feet are more susceptible to injury and infection that heals much more slowly. In severe cases, foot problems may result in lower-limb amputation.

It is important to prevent injury to the feet by checking and caring for them daily. A foot specialist, called a podiatrist, can help to treat symptoms of type 1 diabetes such as neuropathy, ulcers, blood vessel damage and pain. 

Foot problems related to type 1 diabetes are a major cause of disability and in some cases can require frequent visits to a hospital. 

Skin and mouth conditions

With type 1 diabetes, you can be more prone to bacterial and fungal infections, such as thrush, particularly in the skin and mouth.

Sexual problems

Most people with type 1 diabetes are able to lead normal sex lives. However, men with type 1 diabetes can be at greater risk of erectile dysfunction.


Type 1 diabetes is a very serious health condition that requires lifelong management. It is a significant cause of serious health conditions including heart disease, stroke, kidney failure and blindness. However, by effectively managing the level of glucose in the blood, having regular check-ups and seeking treatment early for any complications that occur, it is possible to reduce the risk of these health problems.


It is not possible to prevent type 1 diabetes at present, although research into how this might be possible is ongoing. 

Last Reviewed: 03/10/2018

Reproduced with permission from Health&.