What is diabetes?
Key messages
    • Diabetes is a serious, long-term condition that occurs when the body cannot produce any or enough insulin or cannot effectively use the insulin it produces.The main categories of diabetes are type 1, type 2 and gestational diabetes mellitus.

    • Type 1 diabetes is the major cause of diabetes in childhood but can occur at any age. At present, it cannot be prevented. People with type 1 diabetes can live healthy and fulfilling lives but only with the provision of an uninterrupted supply of insulin, education, support and blood glucose testing equipment.

    • Type 2 diabetes accounts for the vast majority (around 90%) of diabetes worldwide. It can be effectively managed through education, support and adoption of healthy lifestyles, combined with medication as required.Evidence exists that type 2 diabetes can be prevented and there is accumulating evidence that remission of type 2 diabetes may be possible for some people.
    • 'Prediabetes'is a term increasingly used for people with impaired glucose tolerance and/or impaired fasting glucose.It signifies a risk of the future development of type 2 diabetes and diabetes-related complications.

    • Pregnant women with gestational diabetes mellitus can have high blood pressure and babies that are large for gestational age, increasing the risk of pregnancy and birth complications both for the mother and baby.

Diabetes mellitus, more simply called diabetes, is a serious, long-term (or "chronic") condition that occurs when there are raised levels of glucose in a person's blood because their body cannot produce any or enough of the hormone insulin, or cannot effectively use the insulin it produces.

Insulin is an essential hormone produced in the pancreas. It allows glucose from the bloodstream to enter the body's cells where that glucose is converted into energy. Insulin is also essential for the metabolism of protein and fat. A lack of insulin, or the inability of cells to respond to it, leads to high levels of blood glucose (hyperglycaemia), which is the clinical indicator of diabetes. The threshold levels for the diagnosis of diabetes can be found in Table 1.1.

Insulin deficit, if left unchecked over the long term, can cause damage to many of the body's organs, leading to disabling and life-threatening health complications such as cardiovascular diseases(CVD), nerve damage (neuropathy), kidney damage (nephropathy) and eye disease (leading to retinopathy, visual loss and even blindness). However, if appropriate management of diabetes is achieved, these serious complications can be delayed or prevented altogether.