For years, type 2 diabetes was called adult-onset diabetes because it usually begins later in life. In recent years, however, as more children have become heavier at earlier ages, type 2 diabetes has increasingly been seen in teenagers and young adults. Of all peo-^ ple with diabetes, more than 90 percent have type 2 diabetes.
Unlike type 1 diabetes, the development of type 2 diabetes is strongly influenced by lifestyle.
There are two underlying causes of type 2 diabetes. One is the development of insulin resistance. This condition causes the tissues of the body to become less sensitive to the effects of insulin. As a result, sugar circulating in the blood does not leave the blood and enter the body's cells as easily. For the blood sugar to be lowered effectively and for the other "jobs" of insulin to be carried out, more insulin is required. The second cause of type 2 diabetes is the inability to increase insulin to cope with increased demand. Insulin resistance, decreased insulin secretion, or both can result in the development of type 2 diabetes.
Various factors contribute to insulin resistance: being overweight, advancing age, a sedentary lifestyle, an inherited susceptibility, and certain hormonal conditions such as polycystic ovary syndrome. We don't completely understand why insulin resistance develops, and there is probably more than one explanation, but recent research suggests that fat cells produce chemicals that cause tissues to resist the effects of insulin. More fat cells, as in obesity, make more of these chemicals. As a result, sugar can't move into cells and begins to accumulate in the blood, especially after meals. The rising blood-sugar levels drive the beta cells to produce more and more insulin to help push the sugar into the cells where it is needed. And since rising blood-sugar levels also worsen insulin resistance, a vicious cycle begins.
An estimated forty million people in the United States have insulin resistance or prediabetes. They have minimally elevated sugar levels because the pancreas is able to keep making enough insulin. However, in 25 to 50 percent, the pancreas, after many years of overwork, slowly loses the ability to maintain these high levels of insulin. It can still make insulin, but not enough to keep blood-sugar levels in the normal range. Over time, blood-sugar levels drift up, resulting in diabetes.
Sometimes, the elevated blood-sugar levels lead to the usual symptoms of diabetes that patients with type 1 diabetes develop: frequent and excessive urination, increased thirst, fatigue, and J_
weight loss. However, in many people who progress from prediabetes to type 2 diabetes, the rise in blood-sugar levels is insidious and may not cause any symptoms. This helps explain why as many as one-third of the people who have type 2 diabetes don't even know that they have it and why the diagnosis is often delayed by as much as nine to twelve years. It is important to identify blood-sugar problems early on so that you can begin a program to prevent diabetes or if you already have it so you can begin to take care of it and prevent its complications. As with type 1 diabetes, tight control of blood-sugar levels is required to prevent serious and even life-threatening complications.
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