Type 1 diabetes is sometimes called juvenile diabetes because it often develops in childhood or adolescence.
In the past, type 1 diabetes was usually diagnosed in children, while type 2 diabetes was often diagnosed in adults. The term "juvenile diabetes" was used to distinguish type 1 from type 2.
However, our understanding of diabetes has grown and we now know that both type 1 and type 2 diabetes can occur at any age. As a result, the term juvenile diabetes is used less.