What is diabetes?

Patients with diabetes has blood glucose reading Patients living with diabetes must take regular blood glucose readings

Diabetes is an incurable condition in which the body cannot control blood sugar levels, because of problems with the hormone insulin. There are two main variations of the illness, Type I and Type II.

How does the body control blood sugar levels?

Your body uses blood sugar (glucose) for energy. Glucose is a basic ingredient of sweet foods such as sweets and cakes. It can also be produced by carbohydrates such as potatoes, pasta or bread when they are digested and broken down.

Under normal circumstances, the hormone insulin, which is made by your pancreas, carefully regulates how much glucose is in the blood. Insulin stimulates cells all over your body to absorb enough glucose from the blood to provide the energy, or fuel, that they need.

After a meal, the amount of glucose in your blood rises, which triggers the release of insulin. When blood glucose levels fall, during exercise for example, insulin levels fall too.

How the body controls blood sugar levels How the body controls blood sugar levels

Types of diabetes

There are two main types of diabetes. In Type 1 diabetes the cells of the pancreas stop making insulin. In Type 2 diabetes, either the pancreas cells do not make enough insulin, or the body's cells do not react properly to it. This is known as insulin resistance.

Type 1 diabetes is an autoimmune condition, and the immune system attacks the cells of the pancreas. It tends to affect people before the age of 40, and often follows a trigger such as a viral infection.

The exact mechanisms that lead to Type 2 diabetes are not fully understood, but an underlying genetic susceptibility is usually present. This could be a family history of the illness, for example. The condition is then triggered by lifestyle factors - such as obesity - and it usually appears in people over the age of 40.

Type 1 and Type 2 diabetes The cells of people with diabetes cannot properly absorb glucose from the blood

There are three other, less common, forms of diabetes:

  • Gestational Diabetes - During pregnancy, some women experience heightened blood sugar levels and can't produce enough insulin to absorb it all. In most cases it develops between the 14th and 26th week of pregnancy, known as the second trimester, and disappears after the baby is born.
  • Neonatal diabetes - This is very rare. It is caused by a change in a gene that affects insulin production.
  • Maturity onset diabetes of the young (MODY) - Caused by a mutation in a single gene and is also very rare.

How diabetes causes health problems

If people living with Type 1 diabetes don't receive treatment they can develop very high blood sugar levels - hyperglycaemia - within days. Because there is no insulin to drive the sugar from the blood into the cells, the kidneys try to remove the excess glucose. This leads to frequent urination, dehydration and intense thirst.

At the same time, the body starts breaking down fat for fuel to counter the low levels of sugar available to the cells. This leads to toxic levels of acids building up in the blood - a life-threatening condition known as ketoacidosis.

What is the future for diabetes treatment?

Boy having his blood sugar tested

Could there be a future without diabetes?

The family living with type 1 diabetes

Those with Type 1 can also suffer a dangerous complication of treatment known as hypoglycaemia, which can cause a coma. This occurs when blood sugar levels fall dangerously low as a result of taking too much insulin, or sometimes by skipping a meal. The brain requires a constant supply of glucose from the blood otherwise it can't function properly.

If treatment doesn't effectively control high blood sugar levels, it leaves a person with diabetes more vulnerable to infections. Over time it can also damage the small blood vessels and nerves throughout the body, including the smaller vessels at the back of the eye, which can result in blindness, and the kidneys, leading to kidney failure.

Type 2 diabetes tends to develop more gradually, which is one of the reasons why medical professionals think that so many cases go undiagnosed.

In the long-term, diabetes raises the risk of many conditions, including peripheral vascular disease (when the arteries to the extremities are damaged by atherosclerosis) and peripheral nerve damage. Together they can result in ulcers, infections, gangrene and amputations. It can also increase the risk of impotence, heart attacks and strokes.

For more information on symptoms and treatments, please visit NHS Choices

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