It was previously known as the insulin dependent or juvenile onset or childhood onset diabetes. It is a slowly progressive autoimmune disease where the immune system misinterprets the insulin secreting pancreatic cells as foreign cells and destroys it leading to insulin deficiency.

Both male and female are equally affected. The usual onset is in childhood and in early adults not less than 30 years of age. It is lethal unless promptly diagnosed and treated. The incidence is highest among 10–14-year-old group.

In undiagnosed patients there will be severe hyperglycemia which leads to increased thirst (polydipsia) excretion of urine(polyuria), dehydration, hypotension, tiredness, weight loss and are prone to urinary and genital infections. These patients may also be linked to other autoimmune conditions like celiac disease, pernicious anemia, vitiligo, thyroid diseases etc.