Diabetes is a disease characterized by an increase of blood glucose (a sugar) caused by decreased production of the hormone insulin and/or increased resistance to the action of insulin by certain cells. Glucose is the body’s main fuel. When you eat carbohydrates (pasta, bread, rice, grains, fruits, and vegetables), your digestive system breaks them down into glucose, which is released into the bloodstream so your body can use it for energy. Glucose also gets stored in the liver as glycogen, which can later be broken down back into glucose when the body needs fuel.
Insulin, which is produced in the pancreas, regulates both the movement of glucose into the body’s cells and the breakdown in the liver of glycogen into glucose. Both actions are critical to keeping blood sugar levels within normal ranges.
About 1.5 to 2 million people in the U.S. have a form of the disease called type 1 diabetes. In this condition — usually diagnosed in childhood or the early teen years – the pancreas, over a relatively brief period of time, stops producing insulin altogether. The onset of the disease is usually abrupt, with severe symptoms that require immediate attention. Type 1 diabetes is an “autoimmune” disease, which means the body attacks itself. Specifically, aberrant immune cells damage and destroy the part of the pancreas that produces insulin. People with type 1 diabetes must inject insulin every day.
In type 2 diabetes, the pancreas produces enough insulin, at least in the early years of the disease. But for reasons that are still not well understood, the body’s cells become resistant or insensitive to it. To compensate, the pancreas pumps out increasing amounts of insulin to normalize blood glucose levels. Over time — as long as a decade — this ever-increasing production becomes unsustainable, and the pancreas’ ability to produce insulin declines.
As a result, the telltale marker — and problem — of diabetes emerges: glucose levels rise in the blood because it is unable to enter the body’s cells. The excess glucose is damaging to the body’s tissue and leads to the symptoms and complications of diabetes. When the blood glucose level gets high enough, the sugar begins to appear in the urine and causes increased urination.
Elevated blood sugar puts a strain on almost every organ and other parts of the body. Over years, it is particularly toxic to the body’s blood vessels; it causes them to thicken. This leads to problems in the eyes and kidneys, the heart, the liver, and the blood circulation system. High blood sugar also damages the nerves. Proper treatment that keeps blood sugar in the normal range sharply reduces the risk of these complications.