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.

In 2010, there were approximately 3.1 million people aged 16 or over with diabetes (both diagnosed and undiagnosed) in England. By 2030, this figure is expected to rise to 4.6 million, with 90% of those affected having type 2 diabetes.

The charity Diabetes UK estimates that around 850,000 people in England have diabetes but haven’t been diagnosed.

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 pre-diabetes. 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.

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 type 1 diabetes and 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.

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

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. 

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.

The Map of Medicine is used by doctors throughout the NHS to determine the best treatment options for their patients. NHS Choices offers everyone in England exclusive and free access to this cutting-edge internet resource, which lets you see exactly what your doctor sees.

The information in the Map has been approved by the UK’s leading clinical experts, is based on the best available clinical evidence, and is continually updated. To take advantage of this unique resource go to:

Map of Medicine: Type 1 diabetes mellitus in children and adolescents