Type 1 diabetes is most common in children and adolescents (over 95 percent before the age of 25). Therefore, it is also called juvenile diabetes. In this type, ß-cell destruction in the Islets of Langerhans of the pancreas leads to a total deficiency of insulin.

Type 1 Diabetes as an immunity disorder:
Type 1 Diabetes is associated with autoimmune disorder. The body's immune system starts seeing its own tissues, that is, the islet cells of the pancreas, as foreign. Antibodies are thus created to fight the "foreign" tissue and destroy the islet cells’ ability to produce insulin. This results in diabetes. Medical science is still not very certain about the exact reason why this happens. It appears to be a genetic tendency. It is possible that the autoimmune attack could be triggered by an infection, often by one of the Coxsackie virus family. Some types of poisons work by selectively destroying the beta cells, producing Type 1 diabetes. Other common rare causes of Type 1 Diabetes include damage to the pancreas from toxins and trauma.

This autoimmune process can be a long one. As the insulin production is dangerously low, type 1 diabetes usually appears of a sudden and progresses quickly. Warning signs of type 1 diabetes include:

Symptoms

• Polyuria (frequent urination) and Polydipsia [increased thirst (especially for sweet, cold drinks)]. This occurs because of osmotic effects as high glucose (above the 'renal threshold') in the blood has to be excreted by the kidneys in the form of urine. The lost blood volume has to be replaced from water held inside body cells, causing dehydration.
• Increased appetite, even extreme hunger (since glucose does not reach the cells to give energy)
• Sudden, even dramatic, weight loss
• Lethargy, weakness· Blurred vision (due to changes in the retina)
• Smell of acetone on the breath (a dangerous symptom, a sign of ketoacidosis)
• Kussmaul breathing (a rapid, deep breathing)
• Nausea and vomiting (acute symptoms).

A recurrence of bed-wetting after toilet training has been completed is a general symptom in children. Such children may also be restless and apathetic. In severe cases, diabetic coma may be the first sign of type 1 diabetes.

Causes of diabetes
This is a medically and economically important disease, almost an epidemic. Both type 1 and type 2 diabetes are partly inherited. It is even becoming possible to sometimes trace the cause to a single defective gene.

Type 1 diabetes could be triggered by infection, stress, or environmental factors. Type 2 diabetes has a stronger inheritance pattern. Monozygotic twins are at nearly 100% risk; 25% of the patients have a family history of diabetes. Approximately 38% of siblings are likely to develop diabetes or abnormal glucose metabolism at some point.

Other causes of diabetes could relate to unhealthy habits as smoking and lack of physical exercise. As per statistics, certain ethnic groups as Africans, Latinos, Hispanics and Asians are possibly more at risk. The "urbanisation phenomenon" for the rise in Type 2 diabetes has been most carefully studied in non-white populations, but probably, it has no ethnic and racial connections, and is influenced more by age, obesity and genetic factors.