The most common endocrine disorder, and a serious public health problem, is diabetes mellitus, a failure of the body cells to use glucose effectively. The excess glucose accumulates in the blood, causing hyperglycemia. Increased urination (polyuria) marks the effort to eliminate the excess glucose in the urine, a condition termed glycosuria. The result is dehydration and excessive thirst (polydipsia). There is also weakness, weight loss, and extreme hunger (polyphagia). Unable to use carbohydrates, the body burns more fat. This leads to accumulation of ketone bodies in the blood and a shift toward acidosis, a condition termed ketoacidosis. If untreated, diabetes will lead to starvation of the central nervous system and coma. Diabetic patients are prone to cardiovascular, neurologic, and vision problems, infections, and, sometimes, renal failure.
There are two types of diabetes mellitus. Heredity seems to be a factor in the appearance of both. Type 1, also called juvenile-onset or insulin-dependent diabetes mellitus (IDDM), usually appears in children and teenagers. It is caused by a failure of the pancreatic islets to produce insulin, resulting, perhaps, from autoimmune destruction of the cells. Because insulin levels are very low or absent, patients need careful monitoring and administration of this hormone. Blood sugar level may be tested multiple times during the day, and insulin may be given in divided doses by injection or by means of an insulin pump that delivers the hormone around the clock (continuous subcutaneous insulin infusion; CSII). Diet must be carefully regulated to keep glucose levels steady. Insulin is obtained from animals and is now also made by genetic engineering.
Type 2 diabetes mellitus, also called adult-onset or non–insulin-dependent diabetes mellitus (NIDDM), accounts for about 90% of diabetes cases. Type 2 diabetes is initiated by cellular resistance to insulin. Feedback stimulation of the pancreatic islets leads to overproduction of insulin and then to reduced insulin production by the overworked cells. Metabolic syndrome (also called syndrome X or insulin resistance syndrome) is the term now used to describe a state of hyperglycemia caused by insulin resistance in association with some metabolic disorders, including high levels of plasma triglycerides (fats), low levels of high-density lipoproteins (HDLs), hypertension, and coronary heart disease.
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