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Types and Pathogenesis of Diabetes

Type 1 Diabetes mellitus

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Type 1 DM(T1DM) is an autoimmune disease which results when the body’s immune system attacks and destroys the insulin-producing beta-cells in the pancreas.1 As a consequence, the pancreas produces little or no insulin. It is still unknown what exactly causes this attack to the beta-cells but, the autoimmune, genetic and environmental factors including exposure to certain viruses may be involved.1

Earlier, known as insulin-dependent diabetes or juvenile diabetes, T1DM develops most often in children and young adults but can appear at any age. Although beta-cell destruction can begin years earlier, symptoms of T1DM usually develop over a short period. If not diagnosed and treated appropriately, T1DM patients can be affected by life-threatening diabetic coma, known as diabetic ketoacidosis.
Although there is no preventive measure against T1DM, advances in blood glucose monitoring and insulin delivery have simplified its management. With proper treatment, T1DM patients can expect to live healthy and long life.

Type 2 Diabetes mellitus

Type 2 DM (T2DM), previously defined as non-insulin-dependent diabetes mellitus is the most common form, affecting 90–95% of all individuals who develop DM.2 The etiology of T2DM is multifactorial. It is most often associated with older age, obesity, family history of diabetes, previous history of gestational diabetes, sedentary lifestyle and certain ethnicities. Nevertheless, this type is increasingly being diagnosed in children and adolescents lately.

Type 2 DM is characterized by an insulin deficiency or resistance (although the pancreas produces enough insulin, it is not used effectively by the body). The onset of T2DM is not as sudden as T1DM and the symptoms develop gradually. This form of diabetes can be delayed or prevented through lifestyle modifications and/or pharmacological interventions.Maintaining an optimal body weight and being physically active may help prevent the development of T2DM.
Many people with T2DM eventually need insulin therapy to control their blood glucose levels, either as monotherapy or in combination with OHAs. Cardiovascular complications are the most prominent cause of morbidity and mortality in patients with T2DM.4

Gestational Diabetes mellitus

Gestational DM (GDM) refers to carbohydrate intolerance that develops during the 24th to 32nd week of pregnancy in women who had not been previously diagnosed with diabetes. Gestational diabetes is caused by the hormones of pregnancy or a shortage of insulin. Women with GDM may not experience any symptoms.

Screening tests for GDM are performed around the 24th to 28th week of pregnancy. Although GDM usually disappears after the birth of the baby, it is an indicator of greater risk of developing T2DM within the next 5–10 years.2 Patients diagnosed with GDM should be given nutrition counseling and asked to monitor their blood glucose levels in order to maintain normoglycemia. Patients not meeting these goals with dietary changes should be started on insulin therapy.

Anumber of complications are associated with GDM including the risk of preeclampsia, postpartum hemorrhage (excessive bleeding after delivery), higher rates of perinatal mortality, macrosomia (big baby) and neonatal hypoglycemia (low blood glucose).5         

Other Specific Types

This type refers to other forms of diabetes of various known etiologies. It includes patients with genetic defects of beta-cell function (formerly called MODY or maturity-onset diabetes in youth) or with defects of insulin action, patients with diseases of the pancreas such as pancreatitis or cystic fibrosis, patients with dysfunction associated with other endocrinopathies (disorders in the function of endocrine glands and the consequences thereof) and patients with pancreatic dysfunction caused by infections, drugs and chemicals.

Next page: Symptoms of Diabetes

Written by: Healthplus24 team
Date last updated: July 27, 2012