Type 1 diabetes

Type 1 diabetes is a lifelong condition in which the body can't control levels of glucose in the blood. It develops when the body can’t produce the hormone insulin. Type 1 diabetes is sometimes called insulin-dependent diabetes.

About type 1 diabetes

Around 2.6 million people in the UK have been diagnosed with diabetes. About one in 10 of these people have type 1 diabetes. It can develop at any age, but usually affects people before the age of 40, and most commonly during childhood.

Type 1 diabetes develops when your body can’t produce the hormone insulin. Insulin regulates the level of glucose in your blood. Glucose is a simple form of sugar found in foods and sugary drinks. It's absorbed by your body as a natural part of digestion and is carried around your body in your blood. When glucose reaches your body tissues, such as muscle cells, it's absorbed and converted into energy.

Insulin is secreted into your blood by your pancreas, which is a gland located behind your stomach. A shortage of insulin causes glucose to build up in your blood.

Types of diabetes

There are two main types of diabetes: type 1 and type 2. About two million people in the UK have diabetes. Type 1 diabetes is the rarer form, affecting between five and 10 of every 100 people with diabetes.

Symptoms of type 1 diabetes

If you have type 1 diabetes, you may: 

• pass more urine than usual
• be constantly thirsty
• have unexplained weight loss
• be extremely tired
• have blurred vision
• be irritable

The symptoms can develop quickly, usually over a few weeks.

If you have any of these symptoms, see your GP.

Complications of type 1 diabetes

If type 1 diabetes isn't diagnosed or controlled properly, you can develop blood glucose levels that are either too high (hyperglycaemia) or too low (hypoglycaemia).

Hyperglycaemia

Your blood glucose levels can become too high if you’re stressed or unwell, your insulin dose is too low, you miss doses, or if you eat too much carbohydrate. Hyperglycaemia can cause you to be more thirsty than usual, feel tired and have headaches.

Rarely, glucose can build up in your blood and reach dangerous levels. This is called diabetic ketoacidosis. It can cause you to vomit, breathe faster than usual and have breath that smells of ketones (like pear drops or nail varnish). Diabetic ketoacidosis is a medical emergency and can be fatal if you aren’t treated in hospital immediately.

In the long-term, hyperglycaemia can increase your risk of:

• kidney failure
• nerve damage
• blindness
• heart disease
• stroke 

Hypoglycaemia

Your blood glucose levels can become too low if you don't eat enough foods that contain glucose, take too much insulin, or do more physical activity than usual. Hypoglycaemia can cause you to feel faint, sweaty, confused and you may feel your heart pounding. Treat it straight away by eating glucose tablets (or a few sweets or a sugary drink), followed by a couple of biscuits or a sandwich. If you don't treat hypoglycaemia, you may become unconscious and if severe, it can be fatal.

Causes of type 1 diabetes

Type 1 diabetes develops when the cells in your pancreas that make insulin (beta cells) are destroyed by your body's immune system. Because of this, type 1 diabetes is known as an autoimmune disease. However, the way in which type 1 diabetes first starts isn’t fully understood at present, but it's possible it may be caused by a virus or run in families.

Diagnosis of type 1 diabetes

Your GP will ask about your symptoms and examine you. He or she may also ask about your medical history.

You may need to have the following tests.

• Urine test. You will need to give a sample to be tested for glucose and ketones.
• Fasting blood glucose test. Your GP will arrange for you to have a sample of blood taken from your arm to test for glucose.

If your urine tests positively for ketones and you have a raised blood glucose level, this suggests a diagnosis of type 1 diabetes.

If you're diagnosed with type 1 diabetes, you will usually be referred to a clinic that has nurses and doctors who specialise in treating diabetes.

Treatment of type 1 diabetes

There isn't a cure for type 1 diabetes but you can control it with medicines and lifestyle changes. You will need to monitor your blood glucose level carefully.

Medicines

Type 1 diabetes is controlled by giving your body insulin. This helps glucose to be absorbed into your cells and converted into energy, which stops it building up in your blood.

There are two main ways of taking insulin.

• Insulin injections. These are the most common form of treatment, where you inject insulin under your skin. You will usually inject yourself before meals, using either a small needle or a pen-type syringe with replaceable cartridges.
• Portable insulin pumps. These may be appropriate if you find it difficult to control your blood glucose with regular injections, despite careful monitoring. Insulin pumps can be programmed to inject you with insulin at a rate that you can control.

There are several different kinds of insulin that work at different rates and act for different lengths of time. Ask your doctor or diabetes specialist nurse for advice on which type and method is best for you.

Self-help

By making the following lifestyle changes you can help control your blood glucose levels.

• Eat a healthy, balanced diet with regular meals, three times a day. Include carbohydrates, such as pasta or potatoes, in each meal. If you have hypoglycaemia from time to time, it's a good idea to keep some sugary food or glucose tablets with you.
• Aim to do 150 minutes of moderate exercise over a week in bouts of 10 minutes or more. This will help you to stay a healthy weight and control your blood glucose levels.
• Only drink alcohol in moderation and stick within the recommended daily limits.
• If you smoke, give up. Smoking is unhealthy for everyone, but it's especially important to stop if you have diabetes because you already have an increased risk of developing circulatory problems and cardiovascular disease. Smoking makes the chance of you developing these diseases even greater.

Ask at your clinic whether they run structured education classes such as DAFNE (Dose Adjustment For Normal Eating). These are four to five day intensive courses that help you learn how to adjust your insulin dose.

Monitoring your blood glucose level

You can use a home test kit to monitor your blood glucose level. This involves regularly taking a pinprick of blood from the side of your fingertip and putting a drop on a testing strip. A meter will read the result automatically.

Your 'normal' blood glucose range will be specific to you but a general guide for adults is:

• before meals: 4 to 7mmol/L
• after meals: less than 9mmol/L

Your GP or diabetes specialist nurse will show you how to monitor your blood glucose level. He or she will also tell you how often you need to check it.

You may also need to have your levels of glycosylated haemoglobin (HbA1C) tested at least twice a year. HbA1C is a protein that is produced when you have high blood glucose levels over a long period of time. The HbA1C test is done by taking blood from a vein in your arm or sometimes a drop of blood from a fingerprick. It’s used to see how well you’re controlling your blood sugar levels.

For answers to frequently asked questions on this topic, see Common questions.

For sources and links to further information, see Resources.