Type 1 diabetes (T1D), previously known as juvenile diabetes, is an autoimmune disease that originates when very little or no insulin is produced by the islets of Langerhans (containing beta cells) in the pancreas.[4] Insulin is a hormone required for the cells to use blood sugar for energy and it helps regulate normal glucose levels in the bloodstream.[2] Before treatment this results in high blood sugar levels in the body.[1] The common symptoms of this elevated blood sugar are frequent urination, increased thirst, increased hunger, weight loss, and other serious complications.[4][9] Additional symptoms may include blurry vision, tiredness, and slow wound healing.[2] Symptoms typically develop over a short period of time, often a matter of weeks.[1]

The cause of type 1 diabetes is unknown,[4] but it is believed to involve a combination of genetic and environmental factors.[1] The underlying mechanism involves an autoimmune destruction of the insulin-producing beta cells in the pancreas.[2] Recent studies suggest this autoimmune islet destruction may be triggered by persistent enteroviral infections.[10] Diabetes is diagnosed by testing the level of sugar or glycated hemoglobin (HbA1C) in the blood.[5][7] Type 1 diabetes can be distinguished from type 2 by testing for the presence of autoantibodies.[5]