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What is Type 2 Diabetes?
Type 2 diabetes is a chronic disease in which the body's cells have become resistant to insulin. To understand what this means, it helps to understand the roles of glucose and the hormones, insulin and glucagon, in the human body.
Glucose, an important sugar for our body, is absorbed from the foods we eat and transported to the body's cells where it is used as a source of energy. Glucose is the main source of energy for all of the cells in the body. Insulin and glucagon are two hormones that regulate this process, and help maintain stable levels of glucose in the blood.
Normally, when we eat, glucose from food is absorbed by the intestines and enters the bloodstream. In response to this rise in blood-glucose levels, the pancreas releases a hormone called insulin. The insulin binds to receptors in the cells of the body, essentially opening "doorways" in the cells so that glucose can enter the cells from the bloodstream to be used as energy.
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When blood-glucose levels are low, such as when sleeping or in-between meals, a hormone called glucagon is released from the pancreas. Glucagon stimulates glucose that is stored in the liver to be released into the bloodstream, and also causes the liver to produce more glucose.
In type 2 diabetes, the pancreas must produce a large amount of insulin because of the extra glucose in the blood. Just like a muscle that tires of excessive exercise, over a certain time period, the pancreas is not able to keep making large amounts of insulin. As a result, the glucose is unable to enter the cells to be used as energy, and it remains in the bloodstream. This leads to excess glucose in the bloodstream (hyperglycemia). Since there is less glucose entering the cells, the body thinks it needs more glucose for energy and the pancreas releases glucagon. Glucagon causes even more glucose to be produced and released into the bloodstream, raising blood-glucose levels even higher. This hyperglycemia causes the symptoms of diabetes, and over time it can damage the body's organs and lead to further complications.
