See diabetes mellitus for further general information on diabetes.

Diabetes mellitus type 2 (formerly Diabetes mellitus type II and also known as non-insulin-dependent diabetes, NIDDM or adult-onset diabetes) is a metabolic disorder.

The onset of the disease is most common in middle age and later life. It can usually be controlled by diet and exercise, and unlike diabetes mellitus type 1 (juvenile diabetes) it often does not necessitate the use of insulin injections, because insulin production in the pancreas is still possible, although impaired.

The term non-insulin-dependent is a misnomer - some patients must start insulin therapy some time in the course of their disease.

Diabetes mellitus type 2 is often associated with obesity and hypertension, and with the conditions insulin resistance and PCOS or Syndrome X. It is also associated with haemochromatosis, acromegaly, Cushing's syndrome and a number of other endocrinological disorders.