Diabetes mellitus, commonly called dia­betes, is a disorder of metabolism. The cause of diabetes is not known, but it is known that diabetics have a deficiency of insulin, a hormone necessary for the normal utilization and metabolism of sugar. As a result, the blood of diabetics contains excessive quan­tities of sugar, and sugar appears in the urine. Be­cause most people with diabetes have no symptoms, there are many undetected cases. If the disorder pro­duces symptoms, they often include an abnormally great appetite, excessive thirst, increase in the output of urine, and loss of weight.
   It is estimated that more than 26 million people in the United States have diabetes. The disorder occurs among all races and nationalities, and it may appear at any age. Mild diabetes occurs most frequently in middle-aged and elderly persons, especially those who are overweight. When diabetes affects children or adolescents, it is often severe. With proper care most diabetics can live long, healthy, and productive lives.