Final answer:
The most accurate characteristic of type 1 Diabetes Mellitus is the autoimmune destruction of pancreatic beta cells, which leads to insulin deficiency.
Step-by-step explanation:
The characteristic that BEST applies to type 1 Diabetes Mellitus is autoimmune destruction of pancreatic beta cells. Type 1 diabetes, also known as juvenile diabetes or insulin-dependent diabetes, is typically diagnosed in children and young adults. This condition is a chronic autoimmune disorder where the immune system erroneously attacks and destroys insulin-producing beta cells in the pancreas, which results in a lack of insulin production. Unlike type 2 diabetes, which involves insulin resistance, type 1 diabetes is characterized by a complete deficiency of insulin due to the loss of beta cells.