WHO GETS TYPE II DIABETES?
Type II diabetes occurs in both sexes, but women who have had a lot of children and those who have had unusually large babies seem to face a special risk. People who have relatives with diabetes (especially Type II diabetes) have a greater chance of developing the disease themselves.
Diabetes affects all the peoples of the earth, with a few exceptions: It is extremely rare among Eskimos, for example. In the United States, minority groups seem to be especially hard hit: Type II diabetes, the more common form, occurs about 60 percent more often in blacks than in whites, and its prevalence is also very high among Hispanic populations and certain Native American tribes such as the Pimas and Papagos.
The probability of getting Type II diabetes increases with age. The risk also increases with the amount of excess weight. At least three-quarters of the people who develop diabetes in middle or old age are overweight. Yet not all (or even most) overweight people develop diabetes.
What Goes Wrong
Although Type I diabetes is caused by damage to the beta cells of the pancreas, so that they cannot secrete enough insulin, some people with very serious cases of diabetes have beta cells that look perfectly normal. Tests of their blood show plenty of insulin—more than enough, it would seem, to keep the sugar metabolism running smoothly. Yet they too suffer from hyperglycemia.
High blood sugar could result if the pancreas is producing normal amounts of insulin, but the body’s needs for the hormone become far higher than normal and the gland cannot keep up. This might happen when people overeat to an extreme degree, flooding their bodies with more carbohydrates than their system can handle. (In general, any diet that results in a gain in weight will increase one’s chances of developing diabetes. A diet that causes weight reduction will decrease one’s chance of developing diabetes, or, if it is already present, will make it less severe.)
In some cases of diabetes, the insulin that the pancreas produces does not work properly. This may happen for several reasons. For example, the body normally produces a chemical called insulinase, which breaks down excess insulin when its job is done. If too much insulinase is produced, the insulin will be destroyed before it has had a chance to lower the body’s blood sugar level. Sometimes the body produces antibodies against insulin, in much the same way it makes them against disease germs. These anti-insulin antibodies may attack insulin or attach themselves to its molecules so that the hormone cannot work on the cells. Certain drugs, including cortisone, prednisone, contraceptive pills, nicotinic acid, and some diuretics (drugs that are used to rid the body of excess fluids), can interfere with the action of insulin.
Diabetes may also result from hormone disorders, in which the body produces too much glucagon or too much of another pancreatic hormone called somatostatin. This hormone, secreted by the delta cells in the islets, helps to regulate the secretion of both glucagon and insulin.
In non-insulin-dependent diabetes, insulin may not be able to allow glucose to pass into the cells effectively because something is wrong with the outer surface of the cells. Researchers have found that insulin normally reacts with specific chemicals, called receptors, on the cells’ outer membranes. If there are not enough of these receptors, or if they become less receptive to insulin, the hormone will not be able to help glucose get into the cells. This condition is called insulin resistance.
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