Diabetes

Diabetes, more fully diabetes mellitus, is a long-term metabolic condition in which the level of glucose in the blood becomes too high. Glucose is a sugar that the body uses for energy, and it is normally regulated by the hormone insulin. When insulin is missing, insufficient or ineffective, glucose builds up in the blood instead of entering the body's cells properly.

Diabetes affects hundreds of millions of people worldwide and is a leading cause of kidney failure, blindness, limb amputation and cardiovascular disease if it is not managed. With treatment and careful self-care, many people live long and active lives.

Types of diabetes

The main forms are type 1, type 2 and gestational diabetes. Type 1 diabetes is an autoimmune condition in which the immune system attacks the insulin-producing cells of the pancreas. It often appears in childhood or early adulthood and requires lifelong insulin.

Type 2 diabetes is far more common. In type 2, the body's cells respond poorly to insulin, a state called insulin resistance, and the pancreas cannot keep up with the demand. It develops gradually and is linked to genetics, age, excess weight and lifestyle. Gestational diabetes occurs during pregnancy and usually resolves after birth, though it raises the risk of type 2 diabetes later. Other rarer forms exist, including those caused by specific genetic changes or other diseases.

Causes and mechanisms

Insulin allows glucose to move from the bloodstream into cells, where it is used for energy or stored. In diabetes this system breaks down. In type 1, the pancreas produces little or no insulin. In type 2, insulin is produced but the body uses it poorly, and eventually production also falls.

Risk factors differ by type. Type 1 is influenced by genetics and, probably, environmental triggers that are still being studied. Type 2 risk rises with age, excess body weight, inactivity, family history and certain ethnic backgrounds. Some medications and illnesses can also affect glucose control.

Symptoms and diagnosis

Common symptoms include increased thirst, frequent urination, fatigue, blurred vision and slow-healing wounds. Unexplained weight loss is more typical of type 1. Type 2 can develop silently and may be discovered only through testing or when a complication appears.

Diabetes is diagnosed using blood tests that measure glucose levels, such as a fasting glucose test, an oral glucose tolerance test or a long-term marker called HbA1c that reflects average glucose over recent months. Regular screening helps detect type 2 diabetes early, especially in people with risk factors.

Complications

Persistently high glucose damages blood vessels and nerves over time. This can lead to heart disease and stroke, kidney disease, damage to the eyes that may cause vision loss, and nerve damage in the feet that raises the risk of ulcers and amputation. Diabetes also increases susceptibility to some infections.

Acute emergencies exist too. Very high glucose can lead to serious conditions such as diabetic ketoacidosis, especially in type 1, and dangerously low glucose, called hypoglycaemia, can result from certain treatments. Both require prompt attention.

Management

There is no routine cure, but diabetes can be controlled. People with type 1 diabetes need insulin, delivered by injection or pump, and must monitor their glucose closely. Type 2 diabetes is managed with a combination of healthy eating, physical activity, weight control and medications that may include tablets or injectable drugs, with insulin added if needed.

Regular checks of blood pressure, cholesterol, eyes, kidneys and feet help detect and prevent complications. Education and support from health professionals and peers make a real difference in day-to-day control.

Prevention

Type 1 diabetes cannot currently be prevented. Type 2 diabetes can often be delayed or prevented through lifestyle measures such as maintaining a healthy weight, being physically active, eating a balanced diet and avoiding tobacco. Programmes that support these changes have reduced progression to diabetes in people at high risk.

A short history of treatment

Diabetes was described in ancient times, when physicians noticed excessive thirst and urination and the sweet taste of urine. For most of history the condition was poorly understood and often fatal, especially in its type 1 form.

A turning point came in the early 1920s, when Canadian researchers, building on earlier work, extracted insulin and showed it could control blood glucose in people with severe diabetes. Insulin turned type 1 diabetes from a rapidly fatal disease into a manageable long-term condition, and it remains one of medicine's landmark discoveries.

Later advances included improved insulins, home glucose testing, insulin pumps and continuous monitors, and a long list of drugs for type 2 diabetes. These tools, combined with education and lifestyle support, have steadily improved the lives of people with the condition. Genetic research and new technologies such as automated insulin delivery continue to push care forward.

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