Diabetes mellitus is a medical disorder characterized by varying or persistent hyperglycemia (high blood sugar levels), especially after eating. Since insulin is the principal hormone that makes it possible for cells (primarily muscle and fat cells) to use glucose from the blood, deficiency of insulin or its action plays a central role in all forms of diabetes.

Most of the carbohydrates in food are rapidly digested to glucose, the principal sugar in blood. Insulin is produced by beta cells within the Islets of Langerhans in the pancreas. Insulin levels increase in response to rising levels of glucose in the blood, as occurs after a meal. Insulin makes it possible for most body tissue to remove glucose from the blood for use as energy, for conversion to other needed molecules, or for storage. If the amount of insulin produced is insufficient, if cells respond poorly to the effects of insulin (resistance or insulin insensitivity), or if the insulin itself is defective, glucose is not metabolized properly by the cells nor stored appropriately in the liver and muscles. The net effect is that levels of blood glucose remain elevated causing diabetes.

In 2004, according to the World Health Organization, more than 150 million people suffer from diabetes. Its incidence is increasing rapidly, and it is estimated that by the year 2005 this number will double. Diabetes mellitus occurs throughout the world but is more common (especially type 2) in the more developed countries. In 2002 there were about 18.2 million diabetics in the United States alone.

Diabetes is in the top 10 of the most significant diseases in the developed world and is gaining in significance. For the last 20 years, diabetes rates have been increasing substantially in North America. The Centers for Disease Control has determined that diabetes is an epidemic. The National Diabetes Information Clearinghouse estimates that diabetes costs $132 billion per year in the United States.

Diabetes involves multiple casual factors and clinical htmlects, all of which should be well understood for better management of the disease. Patient understanding and participation is a must because blood glucose levels change continuously in response to exercise, diet, physical and psychological stress, infection, accident and hormonal changes, the diabetic patient is the only person experiencing all of these. It is imperative that the patient maintains tight control of blood glucose levels in order to delay and/or prevent complications of diabetes.