Classification of Diabetes Mellitus

Diabetes is a heterogeneous, complex metabolic disorder characterized by elevated blood glucose concentrations secondary to either resistance to the action of insulin, insufficient insulin secretion, or both. The most common classifications include Type 1 diabetes mellitus, Type 2 diabetes mellitus, and gestational diabetes. Type 2 diabetes (T2DM) is characterized by insulin resistance and a relative deficiency of insulin secretion. The absolute plasma insulin concentration (both fasting and meal-stimulated) usually is increased, although "relative" to the severity of insulin resistance, the plasma insulin concentration is insufficient to maintain normal glucose homeostasis. Insulin secretion capacity progressively worsens over time in most patients with T2DM. Type 1 DM results in an absolute deficiency in beta-cell function in most. Autoimmune destruction of beta-cells is a common origin, though cases continue to be classified as idiopathic. Gestational diabetes mellitus (GDM) is defined as glucose intolerance which is first recognized during pregnancy. In most women who develop GDM, the disorder has its onset in the third trimester of pregnancy and patients with GDM have a high risk of developing T2DM later in life. Other causes of diabetes include genetic disorders, diseases that cause damage to the pancreas, as well as an excess of certain hormones such as growth hormone and glucocorticoids. Diabetes mellitus may also be due to drugs, chemicals, or infections. Proper classification of the type of diabetes often helps determine appropriate therapy. For complete coverage of all related areas of Endocrinology, please visit our on-line FREE web-text, WWW.ENDOTEXT.ORG