There are three main types of diabetes: type 1, type 2, and gestational diabetes. Type 1 diabetes is an autoimmune disease where the body attacks the insulin-producing cells, resulting in little to no insulin production. It usually develops in children and young adults and requires daily insulin injections. Type 2 diabetes accounts for 90% of diabetes cases and involves insulin resistance and relative insulin deficiency. It typically develops after age 40 but can occur earlier and is often associated with obesity. Gestational diabetes develops in about one in 25 pregnancies worldwide and involves high blood glucose levels during pregnancy.