Diabetes is a lifelong condition that causes a person's blood sugar level to become too high.
The hormone insulin – produced by the pancreas – is responsible for controlling the amount of glucose in the blood
There are two main types of diabetes:
These pages are about type 2 diabetes. Read more about type 1 diabetes.
Another type of diabetes, known as gestational diabetes, occurs in some pregnant women and tends to disappear after birth.
The symptoms of diabetes occur because the lack of insulin means glucose stays in the blood and isn't used as fuel for energy.
Your body tries to reduce blood glucose levels by getting rid of the excess glucose in your urine.
Typical symptoms include:
Read more about the symptoms of type 2 diabetes.
See your doctor if you think you may have diabetes. It's very important for it to be diagnosed as soon as possible as it will get progressively worse if left untreated.
Read about how type 2 diabetes is diagnosed .
Type 2 diabetes occurs when the body doesn't produce enough insulin to function properly, or the body's cells don't react to insulin. This means glucose stays in the blood and isn't used as fuel for energy.
Type 2 diabetes is often associated with obesity and tends to be diagnosed in older people. It's far more common than type 1 diabetes.
Read about the causes and risk factors for type 2 diabetes.
As type 2 diabetes usually gets worse, you may eventually need medication – usually tablets – to keep your blood glucose at normal levels.
Read more about the treatment of type 2 diabetes.
Diabetes can cause serious long-term health problems. It's the most common cause of vision loss and blindness in people of working age.
Everyone with diabetes aged 12 or over should be invited to have their eyes screened once a year for diabetic retinopathy.
Diabetes is also responsible for most cases of kidney failure and lower limb amputation, other than accidents.
Read more about the complications of type 2 diabetes.
If you're at risk of type 2 diabetes, you may be able to prevent it developing by making lifestyle changes.
If you already have type 2 diabetes, it may be possible to control your symptoms by making the above changes. This also minimises your risk of developing complications.
Read more about living with type 2 diabetes.
The symptoms of diabetes include feeling very thirsty, passing more urine than usual, and feeling tired all the time.
The symptoms occur because some or all of the glucose stays in your blood and isn't used as fuel for energy. Your body tries to get rid of the excess glucose in your urine.
The main symptoms, which are common to both type 1 diabetes and type 2 diabetes, are:
The signs and symptoms of type 1 diabetes are usually obvious and develop very quickly, often over a few weeks.
These signs and symptoms aren't always as obvious, however, and it's often diagnosed during a routine check-up.
This is because they are often mild and develop gradually over a number of years. This means you may have type 2 diabetes for many years without realising it.
See your doctor as soon as possible if you think you may have diabetes. Early diagnosis and treatment for type 2 diabetes is very important as it may reduce your risk of developing complications later on.
Type 2 diabetes occurs when the pancreas, a large gland behind the stomach, can't produce enough insulin to control your blood glucose level, or when the cells in your body don't respond properly to the insulin that is produced.
This means your blood glucose levels may become very high, and is known as hyperglycaemia.
Hyperglycaemia can occur for several reasons, including:
Hyperglycaemia causes the main symptoms of diabetes, which include extreme thirst and frequent urination.
Type 2 diabetes occurs when the pancreas doesn't produce enough insulin to maintain a normal blood glucose level, or the body is unable to use the insulin that is produced ( insulin resistance).
The pancreas is a large gland behind the stomach that produces the hormone insulin. Insulin moves glucose from your blood into your cells, where it's converted into energy.
In type 2 diabetes, there are several reasons why the pancreas doesn't produce enough insulin.
Three of the main risk factors for developing type 2 diabetes are:
People of south Asian and African-Caribbean origin also have an increased risk of developing complications of diabetes, such as heart disease, at a younger age than the rest of the population.
These risk factors are discussed in more detail below.
Read about reducing your risk of type 2 diabetes.
Your risk of developing type 2 diabetes increases with age. This may be because people tend to gain weight and exercise less as they get older.
Maintaining a healthy weight by eating a healthy, balanced diet and exercising regularly are ways of preventing and managing diabetes.
White people over the age of 40 have an increased risk of developing the condition. People of south Asian, Chinese, African-Caribbean and black African origin have an increased risk of developing type 2 diabetes at a much earlier age.
However, despite increasing age being a risk factor for type 2 diabetes, over recent years younger people from all ethnic groups have been developing the condition.
It's also becoming more common for children – as young as seven in some cases – to develop type 2 diabetes.
Genetics is one of the main risk factors for type 2 diabetes. Your risk of developing the condition is increased if you have a close relative such as a parent, brother or sister who has the condition.
The closer the relative, the greater the risk. A child who has a parent with type 2 diabetes has about a one in three chance of also developing the condition.
You're more likely to develop type 2 diabetes if you're overweight or obese.
For most people in the UK, a body mass index (BMI) of:
However, some groups have a higher risk of developing type 2 diabetes:
Fat around your tummy (abdomen) particularly increases your risk. This is because it releases chemicals that can upset the body's cardiovascular and metabolic systems.
This increases your risk of developing a number of serious conditions, including:
Measuring your waist is a quick way of assessing your diabetes risk. This is a measure of abdominal obesity, which is a particularly high-risk form of obesity.
Some groups have a higher risk of developing type 2 diabetes, based on their waist measurements:
Use the BMI calculator to find out if you're a healthy weight for your height.
Exercising regularly and reducing your body weight by about 5% could reduce your risk of getting diabetes by more than 50%.
Read information and advice about losing weight.
Your risk of developing type 2 diabetes is also increased if your blood glucose level is higher than normal, but not yet high enough to be diagnosed with diabetes.
This is sometimes called pre-diabetes, and doctors sometimes call it impaired fasting glycaemia (IFG) or impaired glucose tolerance (IGT).
Pre-diabetes can progress to type 2 diabetes if you don't take preventative steps, such as making lifestyle changes. These include eating healthily, losing weight if you're overweight, and taking plenty of regular exercise.
Women who have had gestational diabetes during pregnancy also have a greater risk of developing diabetes in later life.
Increasing the amount of fibre in your diet and reducing your sugar and fat intake, particularly saturated fat, can help prevent type 2 diabetes, as well as manage the condition if you already have it.
The Diabetes UK website has more information and advice about healthy eating.
If you're overweight or obese – you have a body mass index (BMI) of 30 or over – you should lose weight by gradually reducing your calorie intake and becoming more physically active.
Losing 5-10% of your overall body weight over the course of a year is a realistic initial target.
You should aim to continue to lose weight until you've achieved and maintained a BMI within the healthy range, which is:
If you have a BMI of 30kg/m² or more (27.5kg/m² or more for people of south Asian or Chinese origin), you need a structured weight loss programme, which should form part of an intensive lifestyle change programme.
To help you achieve changes in your behaviour, you may be referred to a dietititian or a similar healthcare professional for a personal assessment and tailored advice about diet and physical activity.
Being physically active is very important in preventing or managing type 2 diabetes.
For adults who are 19-64 years of age, the government recommends a minimum of:
An alternative recommendation is to do a minimum of:
Read more about the physical activity guidelines for adults.
In cases where the above activity levels are unrealistic, even small increases in physical activity will be beneficial to your health and act as a basis for future improvements.
Reduce the amount of time spent watching television or sitting in front of a computer. Going for a daily walk – for example, during your lunch break – is a good way of introducing regular physical activity into your schedule.
If you're overweight or obese, you may need to be more physically active to help you lose weight and maintain weight loss.
Your doctor, diabetes care team or dietitian can give you more information and advice about losing weight and becoming more physically active.
The Diabetes UK website has more information and advice about getting active and staying active.
Type 2 diabetes usually gets worse over time. Making lifestyle changes, such as adjusting your diet and taking more exercise, may help you control your blood glucose levels at first, but may not be enough in the long term.
You may eventually need to take medication to help control your blood glucose levels.
Initially, this will usually be in the form of tablets and can sometimes be a combination of more than one type of tablet. It may also include insulin or another medication that you inject.
Metformin is usually the first medicine used to treat type 2 diabetes. It works by reducing the amount of glucose your liver releases into your bloodstream. It also makes your body's cells more responsive to insulin.
Metformin is recommended for adults with a high risk of developing type 2 diabetes and whose blood glucose is still progressing towards type 2 diabetes, despite making necessary lifestyle changes.
If you're overweight, it's also likely you'll be prescribed metformin. Unlike some other medicines used to treat type 2 diabetes, metformin shouldn't cause additional weight gain.
However, it can sometimes cause mild side effects, such as nausea and diarrhoea, and you may not be able to take it if you have kidney damage.
Sulphonylureas increase the amount of insulin that's produced by your pancreas.
You may be prescribed one of these medicines if you can't take metformin or if you aren't overweight.
Alternatively, you may be prescribed sulphonylurea and metformin if metformin doesn't control blood glucose on its own.
Sulphonylureas can increase the risk of hypoglycaemia (low blood sugar) because they increase the amount of insulin in your body. They can also sometimes cause side effects, including weight gain, nausea and diarrhoea.
Pioglitazone is a type of thiazolidinedione medicine (TZD), which make your body's cells more sensitive to insulin so more glucose is taken from your blood.
It's usually used in combination with metformin or sulphonylureas, or both. It may cause weight gain and ankle swelling (oedema).
You shouldn't take pioglitazone if you have heart failure or a high risk of bone fracture.
Gliptins work by preventing the breakdown of a naturally occurring hormone called GLP-1.
GLP-1 helps the body produce insulin in response to high blood glucose levels, but is rapidly broken down.
By preventing this breakdown, the gliptins (linagliptin, saxagliptin, sitagliptin and vildagliptin) prevent high blood glucose levels, but don't result in episodes of hypoglycaemia.
You may be prescribed a gliptin if you're unable to take sulphonylureas or glitazones, or in combination with them. They're not associated with weight gain.
SGLT2 inhibitors work by increasing the amount of glucose excreted in urine. They may be considered to treat type 2 diabetes if metformin and DPP-4 inhibitors aren't suitable.
The three SGLT2 inhibitors that may be prescribed include:
Each medication is taken as a tablet once a day. The main side effect is a higher risk of genital and urinary tract infections.
Read more about these three new treatment options for type 2 diabetes on the National Institute for Health and Care Excellence (NICE) website.
GLP-1 agonists acts in a similar way to the natural hormone GLP-1 (see the section on gliptins, above).
They're given by injection and boost insulin production when there are high blood glucose levels, reducing blood glucose without the risk of hypoglycaemia episodes ("hypos").
Acarbose helps prevent your blood glucose level increasing too much after you eat a meal. It slows down the rate at which your digestive system breaks carbohydrates down into glucose.
Acarbose isn't often used to treat type 2 diabetes because it usually causes side effects, such as bloating and diarrhoea.
However, it may be prescribed if you can't take other types of medicine for type 2 diabetes.
Nateglinide and repaglinide stimulate the release of insulin by your pancreas. They're not commonly used, but may be an option if you have meals at irregular times.
This is because their effects don't last very long, but they're effective when taken just before you eat.
Nateglinide and repaglinide can cause side effects, such as weight gain and hypoglycaemia (low blood sugar).
If glucose-lowering tablets aren't effective in controlling your blood glucose levels, you may need to have insulin treatment.
This can be taken instead of or alongside your tablets, depending on the dose and the way you take it.
Insulin comes in several different preparations, and each 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 don't last very long (rapid-acting).
Your treatment may include a combination of these different insulin preparations.
Insulin must be injected because it would be broken down in your stomach like food and unable to enter your bloodstream if it were taken as a tablet.
If you need to inject insulin, your diabetes care team will advise you about when you need to do it.
They will show you how to inject it yourself, and will also give you advice about storing your insulin and disposing of your needles properly.
Insulin injections are given using either a syringe or an injection pen, also called an insulin pen (auto-injector). Most people need between two and four injections of insulin a day.
Your doctor or diabetes nurse will also teach a relative or a close friend how to inject the insulin properly.
You can read more about insulin and how to inject it on the Diabetes UK website.
If you have type 2 diabetes that's controlled using insulin or certain types of tablets, you may experience episodes of hypoglycaemia.
Hypoglycaemia is where your blood glucose levels become very low.
Mild hypoglycaemia (a "hypo") can make you feel shaky, weak and hungry, but it can usually be controlled by eating or drinking something sugary.
If you have a hypo, you should initially have a form of carbohydrate that will act quickly, such as a sugary drink or glucose tablets.
This should be followed by a longer-acting carbohydrate, such as a cereal bar, sandwich or piece of fruit.
In most cases, these measures will be enough to raise your blood glucose level to normal, although it may take a few hours.
If you develop severe hypoglycaemia, you may become drowsy and confused, and you may even lose consciousness.
If this occurs, you may need to have an injection of glucagon into your muscle or glucose into a vein. Glucagon is a hormone that quickly increases your blood glucose levels.
Your diabetes care team can advise you on how to avoid a hypo and what to do if you have one.
To reduce your risk of developing other serious health conditions, you may be advised to take other medicines, including:
Diabetic kidney disease is identified by the presence of small amounts of albumin (a protein) in your urine. If treated early enough, it may be reversible.
If you have type 2 diabetes, your doctor or diabetes care team will need to take a reading of your blood glucose level about every two to six months.
This will show how stable your glucose levels have been in the recent past and how well your treatment plan is working.
The HbA1c test is used to measure blood glucose levels over the previous two to three months.
HbA1c is a form of haemoglobin, the chemical that carries oxygen in red blood cells, which also has glucose attached to it.
A high HbA1c level means that your blood glucose level has been consistently high over recent weeks, and your diabetes treatment plan may need to be changed.
Your diabetes care team can help you set a target HbA1c level to aim for. This will usually be less than 59mmol/mol (7.5%). However, it can be as low as 48mmol/mol (6.5%) for some people.
Read more about the HbA1c test .
If you have type 2 diabetes, as well as having your blood glucose level checked by a healthcare professional every two to six months, you may be advised to monitor your own blood glucose levels at home.
Even if you have a healthy diet and are taking tablets or using insulin therapy, exercise, illness and stress can affect your blood glucose levels.
Other factors that may affect your blood glucose levels include drinking alcohol, taking other medicines and, for women, hormonal changes during the menstrual cycle.
If blood glucose monitoring is recommended, you should be trained in how to use a blood glucose meter and what you should do if the reading is too high or too low.
Blood glucose meters aren't currently available for free on the NHS but, in some cases, blood monitoring strips may be. Ask a member of your diabetes care team if you're unsure.
Diabetes UK also provides further information about the availability of blood glucose test strips (PDF, 195kb).
Regularly monitoring your blood glucose levels will ensure your blood glucose is as normal and stable as possible.
As your blood glucose level is likely to vary throughout the day, you may need to check it several times a day, depending on the treatment you're taking.
In home testing, blood glucose levels are usually measured by how many millimoles of glucose are in a litre of blood.
A millimole is a measurement used to define the concentration of glucose in your blood. The measurement is expressed as millimoles per litre, or mmol/l for short.
A normal blood glucose level is 4-6 mmol/l before meals (preprandial) and less than 10 mmol/l two hours after meals (postprandial), although this can vary from person to person.
Your diabetes care team can discuss your blood glucose level with you in more detail.
Eating a healthy, balanced diet is very important if you have diabetes. However, you don't need to avoid certain food groups altogether.
You can have a varied diet and enjoy a wide range of foods as long as you eat regularly and make healthy choices.
You can make adaptations when cooking meals, such as reducing the amount of fat, salt and sugar you eat, and increasing the amount of fibre.
You don't need to completely exclude sugary and high-fat foods from your diet, but they should be limited.
The important thing in managing diabetes through your diet is to eat regularly and include starchy carbohydrates, such as pasta, as well as plenty of fruit and vegetables.
If your diet is well balanced, you should be able to achieve a good level of health and maintain a healthy weight.
As physical activity lowers your blood glucose level, it's very important to exercise regularly if you have diabetes.
Like anyone else, you should aim to do at least 150 minutes (2 hours and 30 minutes) of moderate-intensity aerobic activity, such as cycling or fast walking, every week.
However, before starting a new activity, speak to your doctor or diabetes care team first.
As exercise will affect your blood glucose level, your care team may have to adjust your insulin treatment or diet to keep your blood glucose level steady.
As well as increasing this risk further, smoking also increases your risk of many other serious smoking-related conditions, such as lung cancer.
If you want to give up smoking, your doctor can provide you with advice, support and treatment to help you quit.
If you have diabetes and decide to drink alcohol, avoid drinking more than the recommended daily amounts, and never drink alcohol on an empty stomach.
Depending on the amount you drink, alcohol can cause either high or low blood glucose levels (hyperglycaemia or hypoglycaemia).
Drinking alcohol may also affect your ability to carry out insulin treatment or blood glucose monitoring, so always be careful not to drink too much.
Men and women are advised not to regularly drink more than 14 units a week.
People with long-term conditions, such as type 2 diabetes, are encouraged to get a flu jab each autumn to protect against flu (influenza).
A pneumoccocal vaccination , which protects against a serious chest infection called pneumococcal pneumonia, is also recommended.
If you have diabetes, you're at greater risk of developing problems with your feet, including foot ulcers and infections from minor cuts and grazes.
This is because diabetes is associated with poor blood circulation in the feet, and blood glucose can damage the nerves.
To prevent problems with your feet, keep your nails short and wash your feet daily using warm water.
Wear shoes that fit properly, and see foot care specialists (a podiatrist or chiropodist) regularly so any problems can be detected early.
Regularly check your feet for cuts, blisters or grazes as you may not be able to feel them if the nerves in your feet are damaged.
See your doctor if you have a minor foot injury that doesn't start to heal within a few days.
Read more about feet and diabetes.
If you have type 2 diabetes, you should be invited to have your eyes screened once a year to check for diabetic retinopathy .
Diabetic retinopathy is an eye condition where the small blood vessels in your eye become damaged.
It can occur if your blood glucose level is too high for a long period of time (hyperglycaemia). Left untreated, retinopathy can eventually lead to sight loss.
Read more about diabetic eye screening .
People with diabetes should also see their optician every two years for a regular eye test. Diabetic eye screening is specifically for diabetic retinopathy and can't be relied upon for other conditions.
If you have diabetes and you're thinking about having a baby, it's a good idea to discuss this with your diabetes care team.
Planning your pregnancy means you can ensure your blood glucose levels are as well controlled as they can be before you get pregnant.
You'll need to tightly control your blood glucose level – particularly before becoming pregnant and during the first eight weeks of your baby's development – to reduce the risk of birth defects.
You should also:
Your doctor or diabetes care team can give you further advice.
Read more about diabetes and pregnancy .
Many people find it helpful to talk to others in a similar position, and you may find support from a group for people with diabetes.
Patient organisations have local groups where you can meet others diagnosed with the condition. To find your local diabetes support group, visit Diabetes UK.
If you need to take insulin to control your diabetes, you should have received instructions about looking after yourself when you're ill – known as your "sick day rules".
Contact your diabetes care team or doctor for advice if you haven't received these.
The advice you're given will be specific to you, but some general measures that your sick day rules may include could be to:
Seek advice from your diabetes care team or doctor if your blood sugar or ketone level remains high after taking insulin, if:
If diabetes isn't treated, it can lead to a number of other health problems.
High glucose levels can damage blood vessels, nerves and organs.
Even a mildly raised glucose level that doesn't cause any symptoms can have long-term damaging effects.
If you have diabetes, you're up to five times more likely to develop heart disease or have a stroke.
Prolonged, poorly controlled blood glucose levels increase the likelihood of atherosclerosis , where the blood vessels become clogged up and narrowed by fatty substances.
This may result in poor blood supply to your heart, causing angina, which is a dull, heavy or tight pain in the chest.
It also increases the chance that a blood vessel in your heart or brain will become blocked, leading to a heart attack or stroke.
High blood glucose levels can damage the tiny blood vessels in your nerves.
This can cause a tingling or burning pain that spreads from your fingers and toes up through your limbs. It can also cause numbness, which can lead to ulceration of the feet.
Damage to the peripheral nervous system, which includes all parts of the nervous system that lie outside the central nervous system, is known as peripheral neuropathy .
Diabetic retinopathy is when the retina, the light-sensitive layer of tissue at the back of the eye, becomes damaged.
Blood vessels in the retina can become blocked or leaky, or can grow haphazardly. This prevents light fully passing through to your retina. If it isn't treated, it can damage your vision.
Annual eye checks are usually organised by a regional photographic unit. If significant damage is detected, you may be referred to a doctor who specialises in treating eye conditions (ophthalmologist).
The better you control your blood glucose levels, the lower your risk of developing serious eye problems.
Diabetic retinopathy can be managed using laser treatment if it's caught early enough. However, this will only preserve the sight you have rather than improve it.
If the small blood vessels of your kidney become blocked and leaky, your kidneys will work less efficiently.
It's usually associated with high blood pressure, and treating this is a key part of management.
Damage to the nerves of the foot can mean small nicks and cuts aren't noticed and this, in combination with poor circulation, can lead to a foot ulcer.
About 1 in 10 people with diabetes get a foot ulcer, which can cause a serious infection.
If you have diabetes, look out for sores and cuts that don't heal, puffiness or swelling, and skin that feels hot to the touch. You should also have your feet examined at least once a year.
If poor circulation or nerve damage is detected, check your feet every day and report any changes to your doctor, nurse or podiatrist.
Read more about foot care and diabetes.
In men with diabetes, particularly those who smoke, nerve and blood vessel damage can lead to erection problems. This can usually be treated with medication.
Women with diabetes may experience:
If you experience a lack of vaginal lubrication or find sex painful, you can use a vaginal lubricant or a water-based gel.
Pregnant women with diabetes have an increased risk of miscarriage and stillbirth.
If your blood glucose level isn't carefully controlled during the early stages of pregnancy, there's also an increased risk of the baby developing a birth defect.
Pregnant women with diabetes will usually have their antenatal check-ups in hospital or a diabetic clinic, ideally with a doctor who specialises in pregnancy care (an obstetrician).
This will allow your care team to keep a close eye on your blood glucose levels and control your insulin dosage more easily, as well as monitoring the growth and development of your baby.
The Diabetes UK website has more information about diabetes complications.
The NHS diabetic eye screening programme will arrange for you to have your eyes checked every year.
Everyone who is on a diabetes register will be given the opportunity to have a digital picture taken of the back of their eye. Speak to your doctor to register.
Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.