The most common metabolic disorder is diabetes mellitus. This is a chronic condition that affects how the body processes blood sugar (glucose), leading to high levels of glucose in the bloodstream. There are two main types of diabetes: type 1, which is typically diagnosed in childhood or young adulthood and is caused by the body's immune system attacking and destroying the cells in the pancreas that produce insulin; and type 2, which is more common and is usually diagnosed in adulthood, although it is becoming more common in children and teens as well.    Other common metabolic disorders include metabolic syndrome, hypothyroidism, hyperthyroidism, and hyperlipidemia.