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Diabetes, type 1

Page last reviewed: 13/07/2011

Diabetes is a long-term condition caused by too much glucose, a type of sugar, in the blood. It is also known as diabetes mellitus.

In Ireland, diabetes affects approximately 200,000,people.

How does diabetes occur?

Normally, the amount of sugar in the blood is controlled by a hormone called insulin, which is produced by the pancreas. The pancreas is a gland behind the stomach. When food is digested and enters your bloodstream, insulin moves any glucose out of the blood and into cells, where it is broken down to produce energy.

However, in people with diabetes, the body is unable to break down glucose into energy. This is because there is either not enough insulin to move the glucose, or because the insulin that is there does not work properly.

There are two types of diabetes: type 1 and type 2. This article focuses on type 1 diabetes.

What is type 1 diabetes?

Type 1 diabetes occurs when the body produces no insulin. It is often referred to as insulin-dependent diabetes. It is also sometimes known as juvenile diabetes or early-onset diabetes because it usually develops before the age of 40, often during the teenage years.

Type 1 diabetes is far less common than type 2 diabetes. People with type 1 diabetes make up 10% of all people with diabetes.

If you have type 1 diabetes, you will need to take insulin injections for life. You must also make sure that your blood glucose levels stay balanced by eating a healthy diet and carrying out regular blood tests.

Page last reviewed: 13/07/2011

The main symptoms of diabetes are:

  • feeling very thirsty
  • producing excessive amounts of urine
  • tiredness
  • weight loss and muscle wasting (loss of muscle bulk)

Symptoms of type 1 diabetes can develop quickly, over weeks or even days. Other symptoms are:

  • itchiness around the vagina or penis or getting thrush regularly
  • blurred vision
  • drowsiness
  • cramps
  • constipation
  • skin infections

Symptoms of hyperglycaemia (high blood glucose)

The symptoms of diabetes are due to chronic hyperglycaemia. This happens because there is no insulin to move glucose out of your bloodstream and into your cells to produce energy.

If left untreated, hyperglycaemia can lead to diabetic ketoacidosis, which can eventually cause unconsciousness and even death. Diabetic ketoacidosis occurs when your body begins to break down fats for energy instead of glucose, leading to a build-up of acids in your blood.

When to seek urgent medical attention

Seek urgent medical attention if you have diabetes and you develop:

  • a loss of appetite
  • nausea or vomiting (feeling or being sick)
  • a high temperature
  • stomach pain
  • a fruity smell on your breath, which may smell like pear drops or nail varnish

Want to know more?


Dehydration is an excessive loss of fluids and minerals from the body.
Glucose (or dextrose) is a type of sugar that is used by the body to produce energy.
Insulin is a hormone released by the pancreas that helps the body control blood sugar levels.

Page last reviewed: 13/07/2011

Type 1 diabetes occurs because your body cannot produce insulin. Insulin is a hormone that is needed to control the amount of glucose, a type of sugar, in your blood.

When you eat, your digestive system breaks down food and passes its nutrients into your bloodstream. Normally, insulin is produced by your pancreas to take any glucose out of your blood and move it into your cells, where it is broken down to produce energy.

However, if you have type 1 diabetes, there is no insulin to move glucose out of your bloodstream and into your cells.

What causes type 1 diabetes?

The exact cause of type 1 diabetes is not fully understood, although in most cases it is believed to be an autoimmune condition. This means it occurs as a result of your body's immune system mistaking a natural substance in your body as harmful, and attacking it.

In the case of type 1 diabetes, it is thought that the immune system attacks cells in the pancreas, destroying or damaging them enough to stop insulin production. It is not known exactly what triggers the immune system to do this, but some researchers have suggested that it may be due to a viral infection.

Type 1 diabetes usually runs in families, so there may also be a genetic cause for the autoimmune reaction. If you have a close relative, such as a parent or brother or sister with type 1 diabetes, you have about a 6% chance of developing the condition. The risk for people who do not have a close relative with type 1 diabetes is approximately 0.4%.

In some cases type 1 diabetes may be caused by a condition of the pancreas called chronic pancreatitis.

Chronic pancreatitis causes your pancreas to become inflamed, resulting in severe damage to the cells that produce insulin.

Page last reviewed: 13/07/2011

It is important to diagnose diabetes as early as possible so that treatment can be started. If you experience symptoms, see your GP as soon as possible. They will ask you about your symptoms and ask for a urine sample and measure your blood glucose..

Diagnosis of Diabetes

A urine sample positive for glucose does not diagnose diabetes but may be an indicator that you have the condition as normally the urine does not contain glucose.

Diabetes is diagnosed using a blood test.  If you have symptoms of a high blood sugar then a random blood glucose sample may be sufficient to make the diagnosis.

If you don’t have symptoms of a high blood sugar then a fasting blood glucose sample taken in the morning or a sample used to measure a test called the IFCC (HbA1c), which is an indicator of your blood sugar levels over the preceding 8 to 12 weeks may be sufficient to make the diagnosis.

Very rarely in type 1 diabetes, a test called the oral glucose tolerance test, where you are given a sugary drink is used to diagnosed diabetes.


Page last reviewed: 13/07/2011

Insulin treatment

As type 1 diabetes occurs because your body cannot produce any insulin, you will need to have regular insulin treatment for life to keep your glucose levels normal.

Insulin comes in several different preparations, each of which works slightly differently. For example, some last up to a whole day (long acting), some last up to eight hours (short acting) and some work quickly but do not last very long (rapid acting). Your treatment may include a combination of these different insulin preparations.

Insulin injections

In most cases of type 1 diabetes, you'll need to have insulin injections. Insulin must be injected because if it were taken as a tablet, it would be broken down in your stomach, just like food, and wouldn't be able to enter the bloodstream. When you are first diagnosed, your diabetes healthcare team will help you with your insulin injections, before showing you how and when to do it yourself. They will also show you how to store your insulin and dispose of your needles properly.

Insulin injections are given using a syringe or an injection pen, which is also called an insulin pen or auto-injector. Most people need two to five injections a day. Your GP or diabetes nurse may also teach one of your close friends or relatives how to inject the insulin properly.

Insulin pump therapy

This is an alternative to injecting insulin. An insulin pump is a small device, about the size of a pack of playing cards, that holds insulin.

The pump is attached to you by a long piece of thin tubing, with a needle at the end, which is inserted under your skin. Most people insert the needle just under the skin (subcutaneously) or into their tummy, but you could also insert it into your hips, thighs, buttocks or arms.

The pump allows insulin to flow into your bloodstream at a rate that you can control. This means you no longer need to give yourself injections, although you will need to monitor your blood glucose levels very closely to ensure you are receiving the right amount of insulin.

Insulin pump therapy can be used by adults, teenagers and children (with adult supervision) who have type 1 diabetes. However, it may not be suitable for everyone. Your diabetes healthcare team may suggest pump therapy if you often have hypoglycaemia (low blood glucose).

Want to know more?

Monitoring blood glucose

Monitoring your own blood glucose levels

An important part of your treatment will be making sure your blood glucose level is as normal and stable as possible.

You will be able to manage this using insulin treatment and by eating a healthy diet, but you'll also have to regularly check your blood glucose levels to make sure they are not too high or too low.

Exercise, illness, stress, drinking alcohol, taking other medicines and (for women) changes to hormone levels during your period can all affect your blood glucose levels.

In most cases, you'll need to check your blood glucose levels at home using a simple finger prick blood test. You may need to do this up to four or more times a day, depending on the type of insulin treatment you are taking. Your diabetes healthcare team will talk to you about your ideal blood glucose level.

The normal blood glucose level is 4.0-7.0 mmol/l before meals and less than 9.0 mmol/l two hours after meals. Mmol/l means millimoles per litre, and is a way of defining the concentration of glucose in your blood.

Find out how to test your glucose levels.

Having your blood glucose levels checked

While you need to monitor your own blood glucose levels every day, your GP or diabetes healthcare team will also do a special blood test every two to six months. This shows how stable your glucose levels have been over the past six to twelve weeks, and how well your treatment plan is working.

This is known as the IFCC (HbA1c ) test. Unlike the finger prick test that measures blood glucose at a single time, the IFCC (HbA1c) test gives an idea of blood glucose levels over time. 

It measures the amount of haemoglobin, the oxygen-carrying substance in red blood cells, that has glucose attached to it. A high IFCC (HbA1c level) can mean that your blood glucose level is consistently high and your diabetes treatment plan may need to be altered.

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Treating hypoglycaemia (low blood glucose)

 Hypoglycaemia can occur when your blood glucose level becomes very low.  It is a complication of the insulin injections.

Mild hypoglycaemia (or a 'hypo') can make you feel shaky, weak and hungry, and can be controlled by eating or drinking something sugary, such as a fizzy drink (not a diet version), or a small carton of juice or glucose sweets.

If you develop severe hypoglycaemia, you can become drowsy and confused, and you may even lose consciousness. If this occurs, you will need to have an injection of glucagon into your muscle. Glucagon is a hormone that quickly increases your blood glucose levels.

If you have type 1 diabetes, you may need to carry glucagon with you at all times. Your diabetes healthcare team may show several of your family members and close friends how to inject the glucagon into your muscle, should you need it.

Once you begin to come round, you will need to eat something sugary when you are alert enough to do so. If you lose consciousness as a result of hypoglycaemia, there is a risk that it may happen again within a few hours, so you will need to rest afterwards and have someone with you.

If the glucagon injection into your muscle does not work and you are still drowsy or unconscious 10 minutes after the injection, you will need urgent medical attention.

You'll need to have an injection of dextrose (sugary water) into a vein, which must be given by a trained healthcare professional.

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Treating hyperglycaemia (high blood glucose)

Hyperglycaemia can occur when your blood glucose levels become too high. It can happen for several reasons, such as eating too much, being unwell or not taking enough insulin.

If hyperglycaemia occurs, you may need to adjust your diet or your dosage of insulin to keep your glucose levels normal. Your diabetes healthcare team will advise you about the best way to do this.

However, if hyperglycaemia is not treated, it can lead to diabetic ketoacidosis, which can eventually cause unconsciousness and even death.

Diabetic ketoacidosis occurs when your body begins to break down fats for energy instead of glucose, leading to a build-up of acids in your blood. See Symptoms of type 1 diabetestes for the warning signs of diabetic ketoacidosis.

If you develop diabetic ketoacidosis, you will need urgent treatment in hospital. You will be given insulin directly into a vein (intravenously). If you are dehydrated, you may also need to have other fluids given by a drip, including salt solution and potassium.


Other treatments

Type 1 diabetes can lead to long-term complications. If you have type 1 diabetes, you have an increased risk of developing heart disease, stroke and kidney disease. To reduce the chance of this, you may be advised to take:

  • anti-hypertensive medicines to control high blood pressure
  • a statin, such as simvastatin, to reduce high cholesterol levels
  • low-dose aspirin to prevent stroke
  • angiotensin-converting enzyme (ACE) inhibitor, such as enalapril, lisinopril or ramipril if you have the early signs of diabetic kidney disease

Diabetic kidney disease is identified by the presence of small amounts of a protein called albumin in your urine. It is often reversible if treated early enough.

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Page last reviewed: 13/07/2011

If your diabetes is not treated, it can lead to many different health problems. Large amounts of glucose can damage blood vessels, nerves and organs. Even a mildly raised glucose level that does not cause any symptoms can have damaging effects in the long term.

Heart disease and stroke

If you have diabetes, you are up to five times more likely to have heart disease or a stroke than someone without diabetes. Prolonged, poorly controlled blood glucose levels increase the likelihood of atherosclerosis (furring and narrowing of the blood vessels).

This may result in poor blood supply to the heart, causing angina. It also increases the chance that a blood vessel in your heart or brain will become completely blocked, causing a heart attack or stroke.

Nerve damage

High blood glucose levels can damage the tiny blood vessels of your nerves. This can lead to a tingling or burning pain that spreads from your fingers and toes up through your limbs. If the nerves in your digestive system are affected, you may experience nausea, vomiting, diarrhoea or constipation.


Retinopathy is damage to the retina at the back of the eye. Blood vessels in the retina of your eye can become blocked or leaky, or can grow haphazardly. This prevents the light from fully passing through to your retina. If it is not treated, it can damage your vision.

The better you control your blood sugar levels, the less chance you have of serious eye problems. Having an annual eye check through a retinal screening programme or with a specialist (an ophthalmologist or an optometrist) can help pick up signs of a potentially serious eye problem early on so that it can be treated.

Diabetic retinopathy can be managed by laser treatment or eye injections if it is caught early enough. However, this will only preserve the sight you have and will not make it better.

Kidney disease

If the small blood vessels of your kidney become blocked and leaky, your kidneys will work less efficiently. In rare, severe cases, this can lead to kidney failure and a kidney transplant will be necessary.

Foot problems

Damage to the nerves of the foot can mean that small nicks and cuts are not noticed, which can lead to the development of a foot ulcer. About 1 person in 20 with diabetes gets a foot ulcer, which can cause serious infection.

Check your feet every day and report any changes to your doctor, nurse or podiatrist. Look out for sores and cuts that do not heal, puffiness or swelling and skin that feels hot to the touch. You should also have a foot examination at each diabetes clinic visit.

Sexual dysfunction

In men with diabetes, especially those who smoke, damage to the nerves and blood vessels can lead to erection problems. This may be treated with medication.

Women with diabetes may experience a reduced sex drive, reduced pleasure from sex, a lack of vaginal lubrication, a reduced ability to orgasm or painful sex. Women with a lack of vaginal lubrication or who find sex painful can use a vaginal lubricant or water-based gel.

Miscarriage and stillbirth

Pregnant women with diabetes have an increased risk of miscarriage and stillbirth. If their blood sugar level is not carefully controlled in the early stages of pregnancy, there is also an increased risk of the baby developing a serious birth defect.

Pregnant women with diabetes will usually have their antenatal check-ups in hospital or in a diabetic clinic, where doctors can keep a close eye on their blood sugar levels and control their insulin dosage more easily.

Want to know more?


Insulin is a hormone released by the pancreas that helps the body control blood sugar levels.
Kidneys are a pair of bean-shaped organs located at the back of the abdomen, which remove waste and extra fluid from the blood and pass them out of the body as urine.
The retina is the nerve tissue lining the back of the eye, which senses light and colour and sends it to the brain as electrical impulses.

Useful Links

Page last reviewed: 13/07/2011

You can monitor your own blood glucose levels using a simple finger prick test

Finger prick testing

What you will need:

  • blood testing strips
  • blood glucose meter
  • finger pricking device
  • lancets
  • blood glucose monitoring diary
  • sharps box for disposal of sharps

These are available from your GP or hospital.


  1. Before doing a finger prick test, make sure you have all your equipment in a clean, dry place.
  2. Wash your hands and rinse well with warm water (dirty hands can contaminate a blood sample and give an inaccurate result).
  3. Choose your finger and massage it to improve blood circulation.
  4. Pricking the fleshy part of your finger can hurt. Instead, prick the side of the finger away from the thumb. Squeeze your finger gently to obtain a drop of blood.
  5. Apply the drop of blood to the testing strip. The meter will automatically read the result. Note the result in your diary.

Want to know more?

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Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

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