Diabetes is a chronic condition in which the body cannot properly convert food into energy. There are three main types of diabetes: type 1 diabetes, type 2 diabetes, and gestational diabetes. Type 1 diabetes, formerly known as juvenile diabetes, is usually first diagnosed in children, teenagers, and young adults. Type 2 diabetes is the most common type of diabetes. Formerly called adult-onset diabetes, this type of diabetes can develop at any age -- even during childhood. Gestational diabetes develops in some women during the late stages of pregnancy. Diabetes symptoms can include fatigue, nausea, and excessive thirst. Over time, the high blood glucose levels caused by diabetes can lead to several health problems and complications. Treating diabetes involves testing blood glucose regularly, being physically active, and following a healthy food plan, among other things.