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Diabetes type 2 - Background information
What is it?

  • Diabetes mellitus is a group of metabolic disorders in which persistent hyperglycaemia is caused by deficient insulin secretion or by resistance to insulin's actions combined with relative insulin deficiency. Insulin deficiency and insulin resistance leads to the abnormalities of carbohydrate, fat, and protein metabolism that are characteristic of diabetes mellitus.
  • Diabetes mellitus is classified as:
    • Type 1 diabetes — an absolute insulin deficiency causes persistent hyperglycaemia (insulin activity is normal).
    • Type 2 diabetes — insulin resistance and a relative insulin deficiency result in persistent hyperglycaemia.
    • Gestational diabetes — hyperglycaemia develops during pregnancy and resolves after delivery.
    • Other specific types of diabetes — for example, monogenic diabetes (due to a single gene defect, and previously known as maturity onset diabetes in the young).
  • The term 'type 1 diabetes' has replaced the older terms 'insulin-dependent diabetes mellitus (IDDM)' and 'juvenile-onset diabetes'. The older terms are potentially misleading because people with type 2 diabetes may require insulin, and type 1 diabetes can occur during adulthood.
  • The term 'type 2 diabetes' has replaced the older terms 'non-insulin-dependent diabetes mellitus (NIDDM)' and 'adult-onset diabetes'. The older terms are potentially misleading because people with type 2 diabetes may require insulin, and type 2 diabetes can (rarely) occur during childhood.

[WHO, 2006; Holt and Kumar, 2010a; Holt and Kumar, 2010b]

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