What is the primary characteristic of Type I diabetes?

The primary characteristic of Type I diabetes is that the body cannot produce insulin. This condition arises because the immune system mistakenly attacks and destroys the insulin-producing beta cells in the pancreas. As a result, individuals with Type I diabetes typically require external insulin administration to manage their blood glucose levels, since their bodies are unable to synthesize insulin on their own. This complete lack of insulin production distinguishes Type I diabetes from other forms of diabetes, such as Type II, where the body may still produce insulin but does not use it effectively.