Most of our knowledge about diabetes
mellitus has evolved during the past 20 years. We know that it is a very complex disease
with two major types: Type I, or insulin-dependent diabetes mellitus (IDDM), and Type II,
or non-insulin-dependent diabetes mellitus (NIDDM). The causes that lead to Type I
diabetes are not the same as those that lead to Type II.
Heredity is a major factor in the development of diabetes, and it has been well documented
in studies of identical twins. When one identical twin has Type I diabetes, the risk of
the other twin developing Type I is about 50%. However, when one identical twin has Type
II diabetes, the risk of the other twin developing Type II is nearly 100%. Heredity is
more important in the development of Type II than of Type I.
It has been estimated that 80% to 85% of the people who develop Type II diabetes are
obese, that is, excessively overweight. Obesity is the result of eating more calories than
the body uses, and the excess calories are stored in fat tissue. If you over-eat for a
long period of time, you will become obese. As the number of obese people in our
population increases, the number of diabetic individuals also increases. In the obese
person, overproduction of insulin, muscle and fat cell resistance to insulin, and
increased liver production of sugar are important factors in Type II diabetes.
Insulin plays a vital role in maintaining normal blood sugar levels and normal metabolism,
that is, in breaking down, storing, and using carbohydrates, proteins, and fats. In other
words, insulin helps to regulate the bodys fuels.
Insulin resistance-the bodys inability to use the circulating insulin effectively to
lower blood sugar levels-is almost always present in the Type II diabetic. If you are
insulin resistant, you need more insulin to achieve the same blood sugar levels as a
non-diabetic. The body tries to respond by enlarging the insulin-producing cells and
making more insulin. However, the beta cells (the cells in the pancreas that produce
insulin) eventually become exhausted, resulting in decreased insulin secretion. The body
develops an intolerance to sugar, leading to higher than normal blood sugars.
Resistance to insulin action occurs
both in the liver and in the liver and in the fat and muscle cells. In liver resistance,
abnormally high sugar production occurs even if blood sugar levels are already high. Other
insulin resistance occurs because the muscle cells "take in" less sugar. The
cells ability to take in sugar from the blood to use for energy and rebuilding is
controlled by "receptors." Insulin acts as a key to "unlock" these
receptors and allow sugar to enter the cell. Defects in this lock and key system prevent
the sugar from leaving the blood to enter the muscle cells, and high blood sugar levels
result. Fat cells also contribute to insulin resistance, mainly by defects in the
intracellular metabolism, that is, problems in sugar metabolism after the sugar has
reached the cells.
The exhausted beta cells may eventually recover if you follow a weight-reducing diabetic
diet and exercise program. You may also need an oral hypoglycemic agent, which will work
to reduce your insulin resistance and eventually result in normal blood sugar levels. Some
oral hypoglycemic agents also increase insulin secretion. The action of these agents makes
the insulin in the blood more effective, thus lowering the blood sugar levels.
Faulty Insulin Secretion
People with Type II diabetes may
have normal, below normal, or above normal insulin levels. The defect here is in the beta
cells response to the blood sugar level. Therefore, the amount of insulin secreted,
even when blood sugar levels are high, is not enough to lower the blood sugar to normal.
Also, beta cells often do not respond properly to certain fats and amino acids in the
Faulty insulin secretion often occurs in obese patients when beta cells have become
exhausted and unable to respond to heavy sugar intake. Weight reduction, exercise, and, if
needed, an oral hypoglycemic agent permit the exhausted beta cells to recover and often to
resume normal insulin production.
Increased Liver Sugar Production
In Type II diabetes, there is increased liver sugar production which occurs even when
blood sugars are higher than normal. Insulin is available to the liver but the liver
continues to make sugar due to the lack of insulin action in the cells.
Treatment for the Type II Diabetic:
Treatments that are currently available can correct the defect in insulin secretion and