Diabetes mellitus is a group of long-term conditions in which the level of glucose in the blood becomes too high. This happens because the body does not make enough insulin, cannot use insulin properly, or both.
Insulin is a hormone made by the pancreas. It helps glucose move from the blood into cells, where it can be used for energy. Without enough effective insulin, glucose remains in the blood and can damage blood vessels, nerves, eyes, kidneys, and other tissues over time.
Classification
The main types of diabetes are:
- Type 1 diabetes, an autoimmune condition in which the body cannot make insulin. It often starts in childhood or adolescence, but it can develop at any age. Type 1 diabetes is treated with insulin.
- Type 2 diabetes, in which insulin does not work properly or the body does not make enough of it. It is more common than type 1 diabetes and is linked with factors such as age, weight, ethnicity, family history, and physical inactivity.
- Gestational diabetes, which develops during pregnancy and increases the chance of type 2 diabetes later in life.
- Other forms of diabetes, including monogenic diabetes, diabetes related to pancreatic disease, and diabetes caused or worsened by some medicines or endocrine conditions.
Symptoms
Common symptoms of diabetes include:
- Feeling very thirsty.
- Urinating more often than usual, especially at night.
- Feeling very tired.
- Losing weight without trying.
- Blurred vision.
- Cuts or wounds taking longer to heal.
- Recurrent infections or thrush.
Type 1 diabetes can develop quickly and may become urgent. Type 2 diabetes can develop gradually and may not cause obvious symptoms at first.
Diagnosis
Diabetes is diagnosed with blood tests. These may include:
- HbA1c, which reflects average blood glucose over the previous two to three months.
- Fasting glucose, measured after not eating for a set period.
- Oral glucose tolerance test, sometimes used in pregnancy or where diagnosis is uncertain.
- Random blood glucose, especially when symptoms are present.
The correct test and threshold depend on the clinical situation. Diagnosis should be made by a qualified healthcare professional.
Complications
Short-term complications can include:
- Hypoglycaemia, where blood glucose becomes too low. This is most often linked to insulin or some diabetes medicines.
- Hyperglycaemia, where blood glucose becomes too high.
- Diabetic ketoacidosis, a serious emergency that can occur when the body lacks insulin and produces high levels of ketones.
- Hyperosmolar hyperglycaemic state, a severe complication more often associated with type 2 diabetes.
Long-term complications can include:
- Heart disease and stroke.
- Kidney disease.
- Eye disease, including diabetic retinopathy.
- Nerve damage, including peripheral neuropathy.
- Foot ulcers and, in severe cases, amputation.
- Gum disease and other infection risks.
Good diabetes care aims to reduce these risks through glucose management, blood pressure control, cholesterol management, foot checks, eye screening, kidney monitoring, and support for lifestyle changes.
Management
Diabetes management depends on the type of diabetes and the person's needs. It may include:
- Education about glucose monitoring, food, activity, illness, and medicines.
- Insulin therapy, especially for type 1 diabetes.
- Tablets or injectable medicines for type 2 diabetes.
- Weight management, balanced eating, and physical activity.
- Blood pressure and cholesterol management.
- Regular review by a GP, diabetes nurse, specialist diabetes team, or other appropriate clinician.
Some people with type 2 diabetes can reduce glucose levels through weight loss and lifestyle changes, while others need long-term medication or insulin. Type 1 diabetes requires insulin because the body cannot make enough of its own.
Related Conditions
References
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