Secondary diabetes can be defined as a diabetic condition that develops after the destruction of the beta-cells in the pancreatic islets and/or the induction of insulin resistance by an acquired disease (e.g. endocrinopathies) or others. Recently, diabetes mellitus has divided into four distinct types (type 1 diabetes, type 2 diabetes, other specific types of diabetes and gestational diabetes) in the Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus in USA. The categories between secondary diabetes and the other specific types of diabetes might be different a little, some of the latter being described here. The details of the genetic defects in insulin action has been presented elsewhere (see Chapter V-3).