Some patients at diagnosis of diabetes are not clearly a type 1 or type 2 diabetic. A type 2 diabetic may present with ketoacidosis. Some type 1 diabetics may develop the disease slowly despite having the autoimmune characteristics of type 1. Often the diagnosis is diabetes, but classification as type 1 or type 2 takes time and later in the course of the disease, the type is more obvious.
It is important to note that assigning a type of diabetes to an individual depends on clinical presentation and disease progression at the time of diagnosis and some individuals may not fit clearly into a single category or classification. Some individuals may not be clearly classified into type 1 or type 2 diabetes. The onset of type 1 diabetes can be variable in adults and may not present with the classic symptoms seen in children. In addition, there can be difficulties initially diagnosing diabetes in children, adolescents, and adults. A true diagnosis and classification of diabetes may become more apparent over time.