Diabetes as we know it is typically organized into two neat categories: type 1 and type 2. In type 1 diabetes, antibodies from your own immune system destroy the cells which produce insulin. The disease starts suddenly and is usually diagnosed in children. Type 2 diabetes most often develops in adults as a result of insulin resistance (your cells don’t use the insulin well), not insulin production. John Buse, MD, PhD, chief of the division of endocrinology and metabolism, talked with Health.com about a genetic condition which occupies a gray area between type 1 and type 2.