Diabetes mellitus (DM) is a chronic disease that can affect many parts of the body, including the heart, the kidney, the eyes and the nerves. It occurs because there is too much sugar in the blood, either because of a lack of a substance called insulin (type 1 diabetes mellitus) or an inability to use the insulin that the body produces (type 2 diabetes mellitus). In addition to these main types, there are also some less common causes of diabetes, including genetic defects, certain drugs and even certain types of infections.
Type 1 Diabetes Mellitus
Type 1 diabetes mellitus (type 1 DM) is the most common hormone-related disorder in childhood. It occurs when certain cells of the pancreas (a hormone-producing organ in the body) become damaged by the body's own immune system. It is not yet known why the body's immune system does this. What is known, however, is that when these cells, called beta cells, become damaged, they gradually stop producing a crucial substance called insulin. Without insulin, the body is unable to correctly process the sugar that it gets from breaking down the food we eat. So instead of the needed sugar entering the various cells of the body, it simply stays in the bloodstream and accumulates to abnormally high levels. This is called hyperglycemia, and is the primary characteristic of diabetes mellitus. The hyperglycemia, in turn, results in a range of symptoms including thirst, frequent urination, unintended weight loss and fatigue. Treatment of type 1 DM is to replace the insulin that the body is not producing, either via a pump that delivers the insulin continuously, or by injecting insulin several times a day.
Type 2 Diabetes Mellitus
Type 2 diabetes mellitus (type 2 DM) occurs when a condition called "insulin resistance" arises. In this situation, the body is making insulin correctly; however, the muscles, the fat cells and the liver are not able to respond correctly to the insulin. They "resist" the insulin and thus sugar levels in the blood become higher than normal. Being overweight and obese are risk factors for developing type 2 DM; having family members with the disease also increases the risk. Because of the association with obesity, it was once thought that only adults developed this type of diabetes. However, as obesity in children has become more common, type 2 DM in children has also been seen more frequently, accounting for nearly one-third of new cases of diabetes in some areas. Type 2 DM is treated with a combination of diet and weight loss, and may include medications such as metformin to decrease sugar levels in the blood.
Secondary Diabetes Mellitus
This is a term given to any of a wide range of underlying conditions that may also result in diabetes. These are much less common causes than type 1 and type 2 DM, but do occasionally occur. Cystic fibrosis is a disease that affects the pancreas and may result in the development of diabetes. Pancreatitis (inflammation of the pancreas) may also cause symptoms of diabetes, as the pancreas may "shut down" while it is inflamed. Certain genetic abnormalities may cause the insulin-producing cells to be defective, so they do not produce insulin. In this case, a child is born with beta cells that are not working correctly, and diabetes mellitus is the result of the abnormality. Finally, certain drugs (glucocorticoids, Dilantin), can induce diabetes in children, as can certain infections (congenital rubella).
References
- "Nelson Textbook of Pediatrics"; Robert Kliegman, M.D., et. al.; 2007
- "Greenspan's Basic & Clinical Endocrinology"; David G. Gardner and Dolores Shoback; 2007
- "Current Diagnosis & Treatment in Family Medicine"; Jeanette South-Paul et. al.; 2007
