Type 1 diabetes

Previously known as insulin-dependent diabetes mellitus or juvenile diabetes

Type 1 diabetes is a condition that causes the level of glucose (a type of sugar) in your blood to become too high. It happens when your body is not able to produce enough of a hormone called insulin, which controls blood glucose.

Key points

  1. Type 1 diabetes is mainly diagnosed in childhood and is not caused by being overweight or eating sweet foods. It is different to type 2 diabetes.
  2. Insulin is a hormone made by your pancreas. It helps control how much glucose, a type of sugar, is in your blood.
  3. Without insulin, too much glucose stays in your blood rather than passing into your body's cells, where it is used or stored for energy. 
  4. Long term, high glucose levels can cause damage to your eyes, kidneys, blood vessels, heart and feet. 
  5. You need daily injections of insulin to keep your blood glucose levels under control.
  6. Managing type 1 diabetes can take some getting used to, but should not stop you from leading a full and active life.

What causes type 1 diabetes?

Type 1 diabetes is caused by a combination of genetic (inherited from your family) and environmental factors. If a person who has a genetic tendency to develop diabetes comes in to contact with a trigger in the environment, then diabetes may develop. This can happen at any age.

Many people who have a genetic tendency to develop diabetes do not get diabetes, so researchers are trying to find out more about what the environmental triggers are. These triggers are poorly understood but may be common things in our environment such as viruses or stress. The trigger may be different for different people.

If diabetes is triggered, your body's immune system, which normally protects you from infection, begins to attack the insulin-making cells, which are called beta cells, in your pancreas. Your immune system starts to destroy the beta cells, causing a decrease in insulin production. It can take from a few weeks to a few years for all the beta cells to be destroyed.

Symptoms of diabetes do not occur until more than 90% of the beta cells have been destroyed. This means that it is difficult to tell that you are developing diabetes until the symptoms of diabetes occur.

Did you know?

  • Diabetes cannot be caught from another person – it is not contagious.
  • Type 1 diabetes is not caused by eating too much sugar or any other foods.
  • There is nothing you could have done differently to prevent you or your child from getting type 1 diabetes.
  • You cannot grow out of type 1 diabetes and it does not change into type 2 diabetes as you get older.

Insulin deficiency & type 1 diabetes

Insulin is a hormone that acts as a 'key' to move glucose from your blood into your body’s cells where it is used for energy. After you eat, glucose from your food is absorbed through the lining of your stomach into your blood, which increases the glucose levels in your blood. 

  • In someone who doesn’t have diabetes, your body responds to this increase in glucose by releasing insulin from your pancreas. The insulin helps move the extra glucose from your blood into your cells. Blood-glucose levels return to normal.
  • In type 1 diabetes, your pancreas makes little or no insulin, so glucose stays in your blood. This means your blood-glucose levels stay high – known as hyperglycaemia. Also, your cells do not get the glucose they need for energy, so they use fats to provide energy instead. If your body uses fat for energy too often, it can lead to a dangerous build-up of waste products called ketones.
  • Some parts of your body, in particular your brain and red blood cells, need some glucose to function properly.

What are ketones and why are they a problem?

Ketones are a type of acid that is produced when your body burns fat for energy instead of glucose. Using fat for energy some of the time is normal. However, if it goes on for too long it can produce high levels of ketones in your blood. This can be dangerous as it can lead to coma or even death. 

Treating type 1 diabetes means replacing insulin to 'unlock' your cells, letting glucose in and keeping your blood glucose level stable. Successful management of type 1 diabetes involves having insulin injections and balancing what you eat with how active you are each day. 

What are the symptoms of type 1 diabetes? 

The symptoms of type 1 diabetes are caused by high blood glucose levels (hyperglycaemia) and can come on very quickly. People can get quite sick when they first get type 1 diabetes and often need to be in hospital for a few days. Symptoms can include:

  • feeling very thirsty and drinking lots
  • having to pee a lot more than normal
  • bed wetting
  • tiredness
  • having blurred vision
  • rapid weight loss
  • sores that do not heal
  • recurring infections
  • poor concentration and performance

If a diagnosis is not made quickly, severe dehydration can occur.

When should I seek help for diabetes?

If you or your child have any of the above signs and symptoms, and you are concerned, please go to your family doctor or health professional for advice. If you can’t see a doctor for whatever reason, go to the nearest emergency department.

How is diabetes diagnosed?

In most cases the diagnosis of diabetes is simple. A blood test is used to diagnose diabetes. Sometimes your doctor may do a urine test to look for sugar or ketones in your urine. This is a simple test and the results are available immediately but a urine test is not accurate enough to be used to diagnose or rule out diabetes all the time. 

Types of blood tests used to diagnose diabetes

  • Random blood glucose level: This blood test for the level of glucose in your blood can diagnose diabetes, but the result depends on what food you have eaten before the test.
  • HbA1c: This blood test measures the amount of glucose that has accumulated in your blood over a 3-month period. A high HbA1c result confirms the diagnosis of diabetes.
  • Fasting blood glucose: This is a measure of how much glucose is in your blood when you have not eaten anything for the past 8 to 10 hours.

  

Normal

Pre-diabetes

Diabetes

Random glucose

   

≥ 11.1 mmol/l

HbA1c

≤ 40 mmol/mol

41–49 mmol/mol

≥ 50 mmol/mol

Fasting blood glucose

 

6.1–6.9 mmol/l

≥ 7.0 mmol/l

What are the causes of type 1 diabetes?

The exact cause of type 1 diabetes is unknown, but it is thought to be an autoimmune condition. In autoimmune conditions, your body's immune system is confused and attacks your own cells. In type 1 diabetes, the cells that are damaged are the beta cells in your pancreas that make insulin.

When first diagnosed with type 1 diabetes, you may still be producing some insulin. Over time more insulin-producing cells are damaged, until your body can no longer produce any of its own.

What is the treatment for type 1 diabetes?

Type 1 diabetes is a lifelong condition that can be well managed and controlled with the use of artificial insulin. This insulin is used to replace the insulin that your body cannot make. It is not available as an oral medicine – you must inject it into the layer of fat under your skin.

The aim of treatment is to give the right amount of insulin to balance what you eat with how much energy you need throughout the day. Successful management of type 1 diabetes involves:

  • regularly testing your blood glucose level throughout the day
  • taking regular injections of insulin 2 or more times per day
  • eating regular meals and choosing healthy food
  • keeping physically active to keep your heart and blood vessels healthy
  • learning how to fine-tune your insulin doses with different meal sizes and activity levels.

Learn more about insulin.

Self-care for type 1 diabetes

Diabetes is a lifelong condition. If it is poorly managed and blood-glucose levels are not controlled, diabetes increases the risk of serious complications such as problems with vision or blindness, heart attack or stroke, kidney failure, circulatory problems and impotence in men.

With good control of your diabetes, many of these complications can be prevented or slowed down.

Long-term risks and complications can be minimised by:

  • learning as much as you can about diabetes
  • having good medical care – make sure to have your regular check-ups with your doctor or nurse so that potential problems can be found and treated early
  • having a healthy food plan and a regular intake of carbohydrates both for growth and development and to balance insulin and activity levels
  • getting regular exercise and understanding how physical activity affects blood glucose levels
  • watching your cholesterol and blood pressure
  • generally having a healthy lifestyle.

Managing low blood glucose (hypoglycaemia)

Although people with type 1 diabetes are trying to keep your blood glucose level from going too high, it is also important to stop it going too low. If the blood glucose drops below 4 mmol/L, this is called low blood glucose or hypoglycaemia. This can be caused by, eg, injecting too much insulin or not eating enough of the right food at the right time.

Symptoms include sweating, shakiness and lightheadedness, and can lead to unconsciousness if not treated. Low blood glucose must be raised urgently, with quick-acting carbohydrate such as glucose tablets (or glucagon injections if the person is unconscious).

Blood glucose testing

To test your blood glucose level throughout the day, you use a small finger prick test to get a drop of blood that can be put onto a testing strip. The testing strip is inserted into a blood glucose meter and gives a result within seconds.

  • A normal reading is between 4 to 7 mmol/L (glucose is measured in millimoles per litre of blood).
  • Check with your doctor, nurse or pharmacist what your target level should be.
  • If the level is below 4 mmol/L, you will usually need to eat something.
  • If the level is above 7 mmol/L, you may need to alter your insulin dose or do something active.
  • Learning how to balance these levels with what you eat, how much insulin you give yourself and your activity levels are the key to managing your diabetes.

Healthy eating and exercise

What you eat and how much exercise you do affects your blood-glucose levels. The more you eat and the less you exercise, the higher your blood-glucose levels will be and the more insulin you will need. Learning how to fine-tune your insulin doses with different meal sizes and activity levels is part of managing type 1 diabetes.

To help give you more even blood-glucose levels:

  • Eat breakfast, lunch and dinner at regular times of the day, with snacks in between as advised by your dietitian or nurse.
  • Eat healthy, balanced meals with a range of carbohydrates, fats and protein. See heart healthy eating
  • Choose high fibre carbohydrates, eg, wholegrain breads (breads with lots of grainy bits), high-fibre breakfast cereals, legumes, fruit and vegetables and those with a low glycaemic index (GI). Carbohydrate foods with a low GI are digested (broken down to glucose) more slowly.
  • Exercise regularly. 

Stress management and illness with diabetes

Managing stress is especially important. Blood glucose levels are more difficult to control if you are under stress, so you may need to monitor them more frequently.

  • Make sure you know what to do when unwell and have a ‘sick day’ plan.
  • If you are vomiting or have diarrhoea, see a doctor as you are at higher risk of becoming dehydrated.

Support for type 1 diabetes

Most people cope well with support from health professionals, partners, family/whānau, diabetes support groups and diabetes educators. With a clear understanding of the condition, you can lead a normal, fulfilling life.

Kiwis living well with diabetes Diabetes NZ
Children with diabetes Diabetes Youth New Zealand

Regional diabetes support

Learn more

There is a wealth of information now about living well with diabetes. Be aware that websites from other countries may have information that differs from New Zealand recommendations.   

Diabetes in children KidsHealth NZ
Living well with diabetes Diabetes NZ
Type 1 diabetes NHS, UK
Diabetes Projects Trust
 

Credits: Health Navigator Editorial Team. Reviewed By: Jeremy Tuohy, Researcher & Clinician, University of Auckland Last reviewed: 16 Oct 2019