Diabetes is a lifelong condition that causes a person’s blood sugar level to become too high.

There are two main types of diabetes – type 1 diabetes and type 2 diabetes.

Type 2 diabetes is far more common than type 1. In the UK, around 90% of all adults with diabetes have type 2.

There are 3.9 million people living with diabetes in the UK. That’s more than one in 16 people in the UK who has diabetes (diagnosed or undiagnosed).

This figure has more than doubled since 1996, when there were 1.4 million. By 2025, it is estimated that five million people will have diabetes in the UK.

Many more people have blood sugar levels above the normal range, but not high enough to be diagnosed as having diabetes.

This is sometimes known as prediabetes. If your blood sugar level is above the normal range, your risk of developing full-blown diabetes is increased.

It’s very important for diabetes to be diagnosed as early as possible because it will get progressively worse if left untreated.

When to see a doctor

You should therefore visit your GP as soon as possible if you have symptoms, such as feeling thirsty, passing urine more often than usual, and feeling tired all the time.

Symptoms of diabetes

The main symptoms of diabetes are:

  • feeling very thirsty
  • urinating more frequently than usual, particularly at night
  • feeling very tired
  • weight loss and loss of muscle bulk
  • itching around the penis or vagina, or frequent episodes of thrush
  • cuts or wounds that heal slowly
  • blurred vision (caused by the lens of the eye becoming dry)

Type 1 diabetes can develop quickly over weeks or even days.

Many people have type 2 diabetes for years without realising because the early symptoms tend to be general.

What causes diabetes?

The amount of sugar in the blood is controlled by a hormone called insulin, which is produced by the pancreas (a gland behind the stomach).

When food is digested and enters your bloodstream, insulin moves glucose out of the blood and into cells, where it’s broken down to produce energy.

However, if you have diabetes, your body is unable to break down glucose into energy. This is because there’s either not enough insulin to move the glucose, or the insulin produced doesn’t work properly.

Type 1 diabetes

In type 1 diabetes, the body’s immune system attacks and destroys the cells that produce insulin. As no insulin is produced, your glucose levels increase, which can seriously damage the body’s organs.

Type 1 diabetes is often known as insulin-dependent diabetes. It’s 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 less common than type 2 diabetes. In the UK, it affects about 10% of all adults with diabetes.

If you’re diagnosed with type 1 diabetes, you’ll need insulin injections for the rest of your life.

You’ll also need to pay close attention to certain aspects of your lifestyle and health to ensure your blood glucose levels stay balanced.

For example, you’ll need to eat healthily, take regular exercise and carry out regular blood tests.

Read more about living with diabetes.

Type 2 diabetes

Type 2 diabetes is where the body doesn’t produce enough insulin, or the body’s cells don’t react to insulin. This is known as insulin resistance.

If you’re diagnosed with type 2 diabetes, you may be able to control your symptoms simply by eating a healthy diet, exercising regularly, and monitoring your blood glucose levels.

However, as type 2 diabetes is a progressive condition, you may eventually need medication, usually in the form of tablets.

Type 2 diabetes is often associated with obesity. Obesity-related diabetes is sometimes referred to as maturity-onset diabetes because it’s more common in older people.

You can use the BMI healthy weight calculator to check whether you’re a healthy weight.

Read more about type 2 diabetes

Diabetic eye screening

Everyone with diabetes aged 12 or over should be invited to have their eyes screened once a year.

If you have diabetes, your eyes are at risk from diabetic retinopathy, a condition that can lead to sight loss if it’s not treated.

Screening, which involves a half-hour check to examine the back of the eyes, is a way of detecting the condition early so it can be treated more effectively.

Read more about diabetic eye screening.

Gestational diabetes (in pregnancy)

During pregnancy, some women have such high levels of blood glucose that their body is unable to produce enough insulin to absorb it all. This is known as gestational diabetes and affects up to 18 in 100 women during pregnancy.

Pregnancy can also make existing type 1 diabetes worse. Gestational diabetes can increase the risk of health problems developing in an unborn baby, so it’s important to keep your blood glucose levels under control.

In most cases, gestational diabetes develops during the second trimester of pregnancy (weeks 14 to 26) and disappears after the baby is born.

However, women who have gestational diabetes are at an increased risk (30%) of developing type 2 diabetes later in life (compared with a 10% risk for the general population). 

Read more about gestational diabetes.

Diabetic eye screening

Eye screening is a key part of your diabetes care. If you have diabetes, your eyes are at risk of damage from diabetic retinopathy, a condition that can lead to sight loss if it’s not treated.

Diabetic retinopathy occurs when diabetes affects small blood vessels, damaging the part of the eye called the retina. When the blood vessels in the central area of the retina (the macula) are affected, it is known as diabetic maculopathy.

Diabetic retinopathy is one of the most common causes of sight loss among people of working age.

However, you may not know that you have diabetic retinopathy as it does not usually cause any noticeable symptoms in the early stages.

Screening is a way of detecting the condition early before you notice any changes to your vision. 

If retinopathy is detected early enough, treatment can stop it getting worse. Otherwise, by the time symptoms become noticeable, it can be much more difficult to treat.

This is why the NHS Diabetic Eye Screening Programme was introduced. Everyone aged 12 and over with diabetes is offered screening once a year.

The check takes about half an hour and involves examining the back of the eyes and taking photographs of the retina.

Read on to find out when screening is offered, what happens at your screening appointment, and what you’ll learn from your screening results. 

When is diabetic eye screening offered?

Everyone with diabetes who is 12 years of age or over should be invited to have their eyes screened once a year.

You should receive a letter from your local Diabetic Eye Screening Service inviting you to attend a screening appointment. The letter will include a leaflet about diabetic eye screening.

Contact your local screening service or your GP if you have not received a letter and your appointment is overdue. You can look up your local screening service here – your service will be the one nearest to your GP surgery.

The invitation will say where you need to go. This may be your GP surgery, your local hospital, a local optician’s practice, or another nearby clinic.

Bring all the glasses and contact lenses you wear, along with lens solution for contacts.

If you have sight problems in between screening appointments, such as sudden vision loss or a deterioration in your vision, seek immediate medical advice. Do not wait until your next screening appointment.

Diabetic eye screening in pregnancy

If you have diabetes and become pregnant, you will need special care as there are risks to both mother and baby associated with the condition.

You’ll be offered additional tests for diabetic retinopathy at or soon after your first antenatal clinic visit, and also after 28 weeks of pregnancy.

If the early stages of retinopathy are found at the first screening, you will also be offered another test between 16 and 20 weeks of pregnancy.

If serious retinopathy is found at any screening, you will be referred to an eye specialist.

Some women who do not have diabetes can develop hyperglycaemia (high blood sugar) during pregnancy. This is known as gestational diabetes.

Pregnant women who develop gestational diabetes are not offered screening for diabetic retinopathy.

Other eye checks

Diabetic eye screening is not covered as part of your normal eye examination with an optician.

Screening does not look for other eye conditions, so you should continue to visit your optician regularly for an eye examination as well.

What happens during diabetic eye screening?

The screening appointment should last about 30 minutes.

When you arrive, the procedure will be explained to you. If you have any questions, ask the healthcare professional who is treating you.

You will be given eye drops to enlarge your pupils, which takes between 15 and 20 minutes, and photographs of your retina will be taken.

There will be a flash of light each time a photograph is taken, but the camera will not touch your eye. Although the light is bright, it should not be uncomfortable.

The eye drops may cause your eyes to sting slightly, and after about 15 minutes your vision will be blurred. You may find it difficult to focus on objects that are close to you.

Depending on the type of eye drops used, the blurring can last between two and six hours. You won’t be able to drive home from your appointment, so you may want to bring someone with you.

After the screening procedure, you may also find that everything looks very bright. You may want to take a pair of sunglasses to wear afterwards.

Side effects

In very rare cases, the eye drops can cause a sudden pressure increase within the eye.

This will require prompt treatment at an eye unit. The symptoms of a pressure increase are:

  • pain or severe discomfort in your eye
  • redness of the white of your eye
  • constantly blurred vision, sometimes with rainbow halos around lights

If you experience any of these symptoms after screening, go back to the screening centre or your nearest accident and emergency (A&E) department.

Your screening results

Within six weeks, both you and your GP should receive a letter letting you know your results.

You will not get the results immediately as the photographs will need to be studied by a number of different healthcare professionals, including someone who is trained in identifying and grading retinopathy.

The screening results may show either:

  • no retinopathy
  • background retinopathy – also called stage one retinopathy
  • degrees of referable retinopathy – this means retinopathy that requires referral to an eye specialist for further assessment and treatment

You may need to have a further assessment if:

  • the photographs are not clear enough to give an accurate result
  • you have retinopathy that could affect your sight and follow-up treatment is needed
  • you have retinopathy that needs to be checked more than once a year
  • other eye conditions are detected, such as glaucoma (a group of eye conditions that affect vision) or cataracts (cloudy patches in the lens of the eye)

If your results show no retinopathy or background retinopathy, you will be invited back for another screening appointment a year later.

You can also reduce your risk of developing diabetic retinopathy in the future by controlling your blood sugar levels and blood pressure.

Read more about what you can do to prevent diabetic retinopathy.

If screening detects signs that diabetic retinopathy or maculopathy is threatening your sight, you will be given information about how far the condition has progressed. This will determine the type of treatment you receive.

Read about the treatment options for diabetic retinopathy and maculopathy.

If you have questions about your results, contact your local diabetic eye screening service. Their details should be on the letter you received from them. Alternatively, you can find your local screening service here.

For more information on diabetic eye screening, see our diabetic eye screening FAQs.

FAQs on diabetic eye screening

Will I be offered diabetic eye screening if I live outside England?

What evidence is there to support diabetic eye screening?

What if I don’t want to be screened for diabetic eye disease?

What sort of information about me is held by the NHS Diabetic Eye Screening Programme?

Who will see information about me if I have diabetic eye screening?

Is screening for diabetic retinopathy available privately?

Where can health professionals find out more about the Diabetic Eye Screening Programme?

Could I find out about other health problems as a result of diabetic eye screening?

Why is screening not offered to children under 12?

Will I be offered diabetic eye screening if I live outside England?

Diabetic screening programmes have been set up in Northern Ireland, Scotland and Wales. Details are available below:

What evidence is there to support screening?

The UK National Screening Committee (UKNSC) advises ministers and the NHS in all four UK countries on all aspects of screening policy. Its decisions are based on research evidence and informed by multidisciplinary groups including healthcare professionals and patient representatives.

There are six main reasons why the UKNSC recommended a screening programme for sight-threatening diabetic retinopathy:

  • Diabetic retinopathy is an important public health problem. It is among the most common causes of blindness in people of working age in England and Wales.
  • The global epidemic of diabetes, especially type 2 diabetes, means that diabetic retinopathy will continue to be a public health problem.
  • Diabetic retinopathy can be diagnosed at an early stage in people with both type 1 and type 2 diabetes.
  • Laser treatment is an effective treatment for diabetic retinopathy, while there is also evidence that diabetic retinopathy can be prevented or the rate of deterioration slowed through better blood glucose and blood pressure control.
  • There is a suitable and reliable screening test available.
  • Screening and treatment are a cost-effective use of resources.

What if I don’t want to be screened?

People with diabetes can opt out of the screening programme if they choose.

They should confirm this decision in writing to the screening service that has invited them for diabetic eye screening.

What sort of information about me is held by the NHS Diabetic Eye Screening Programme?

The programme receives information about you from your GP practice in order to invite you for screening. This includes your name, date of birth, ethnicity, contact details, NHS number, details of your GP and the fact that you have been diagnosed as having type 1 or type 2 diabetes. If you ask your GP practice not to provide this information to the screening programme, you will not be invited to screening.

During or after your screening appointment, the programme may ask for additional clinical information relating to your diabetes. The programme will only record this type of information if you give your permission. If you do not agree to provide additional clinical information this will not prevent you from being screened in future.

Who will see information about me if I have diabetic eye screening?

Your information will be seen by:

  • Those involved in the administration of the programme.
  • Those who carry out the screening process (including putting in the eyedrops, checking vision, taking your history, taking photographs of your eyes and grading the photographs). These are either staff employed by an NHS body or optometrists, self-employed ophthalmologists or staff employed by independent companies. The programme will provide you with a list of non-NHS personnel and companies if you are concerned in any way about who will see information about you. You should let the programme staff know if you have any particular concerns about any particular individual or company.

If your case is referred to the hospital for further assessment the information about you will be forwarded to the hospital so that those who will be looking after your case can have as much information about your history as possible.

To make sure that the programme operates effectively, from time to time its work is assessed by clinical auditors and others involved in quality assurance. They may need to have access to your data. In addition, efforts will be made nationally to carry out research using fully anonymised data to try to identify as precisely as possible how best diabetes should be managed in the long term. Some examples may be how many people have diabetic retinopathy in any area or how quickly it progresses in different groups of people. Any efforts to use any identifiable information would result in the programme working with the Patient Information Advisory Group to make sure that all necessary agreements are obtained.

Occasionally problems may occur in the software used to support the programme. Normally the software supplier will not need to see any information that identifies a specific individual, but occasionally it may become necessary to supply basic information to ensure that the correct information is maintained by the programme securely. Software suppliers who work with the NHS are bound by requirements of confidentiality and should be supervised by NHS staff if they need to look at information that is linked to a named individual.

Your results and screening information will be sent to your GP.

Is screening for diabetic retinopathy available privately?

Eye checks for diabetic retinopathy are available privately but they won’t necessarily be quality-assured in the same way as the NHS Diabetic Eye Screening Programme. If you have diabetes and are over 12, you are entitled to a free annual screening test provided through the NHS Diabetic Eye Screening Programme. If you qualify for NHS diabetic eye screening and haven’t received your annual invitation, talk to your GP or contact your local diabetic eye screening service.

If you are considering private screening, check that the company is properly regulated and ask for clear written information about the benefits as well as the risks of any tests offered. Find further information in the UK National Screening Committee’s leaflet on private screening.

Where can health professionals find out more about the Diabetic Eye Screening Programme?

Information for health professionals can be found on the NHS Diabetic Eye Screening Programme website.

Could I find out about other health problems as a result of diabetic eye screening?

The screening programme is specifically for diabetic retinopathy and has good detection levels for this condition. It is possible to identify some other conditions on digital photographs, but that is not the purpose of the screening programme so it cannot be relied upon for other conditions. This is why people with diabetes should see their optician every two years for a regular sight test in addition to their annual diabetic eye screening appointments.

Why is screening not offered to children under 12?

The current guidance is to start screening at 12 because diabetic retinopathy is extremely unusual in children with diabetes who are under the age of 12.

Find general information on diabetic eye screening.