10-5. PRODUCTION OF INSULIN IN THE BODY
a. Insulin is produced and stored in the beta cells of the Islets of Langerhans of
the pancreas. Insulin is released from storage in the pancreas into the bloodstream.
b. The level of glucose in the blood is the primary regulator of the secretion of
insulin into the bloodstream. When an individual has not eaten in a long while, the level
of insulin in the blood is at a minimum. Also, some gastrointestinal hormones (i.e.,
cholecystokinin, gastrin, and secretin) and amino acids stimulate insulin secretion. After
the person ingests food, a combination of the presence of amino acids, glucose, and
gastrointestinal hormones acts to stimulate insulin secretion and raise the level of
insulin in the blood. While the level of insulin in the blood is high, the body uses the
glucose in the blood for energy and it converts excess glucose to fat for future energy
10-6. CONDITIONS DUE TO ABNORMAL AMOUNTS OF INSULIN IN THE
The body requires a certain amount of insulin to be present in the blood when the
insulin is needed. Although the level of insulin in the blood does not remain the same
over a 24-hour period, insulin must be present in the blood at all times. The individual
whose pancreas produces and releases insulin in the required amount at the time it is
needed is fortunate indeed. However, not all persons are this fortunate. Diabetes
mellitus is a disorder resulting from inadequate production or use of insulin. If, on the
other hand, a patient has too high a level of insulin--due to the administration of too
much insulin or lack of food after the administration of insulin--the patient's life can be in
danger. These two conditions are discussed in the following section.
Section II. CONDITIONS DUE TO ABNORMAL AMOUNTS
OF INSULIN IN THE BLOODSTREAM
10-7. DIABETES MELLITUS
a. Description. Diabetes mellitus is a disorder characterized by hyperglycemia
(high levels of glucose In the blood) and glycosuria (glucose in the urine) resulting from
inadequate production or use of insulin.
b. Significance. Over 10 million persons in the United States have diabetes
mellitus. Diabetes mellitus affects both young and old alike. Insulin and oral
hypoglycemic agents have helped prolong the life of persons who have diabetes
mellitus. However, persons who have diabetes mellitus, even though it is successfully
treated, sometimes have complications. Remember, diabetes mellitus can be treated,
but it cannot be cured with the administration of either insulin or oral hypoglycemics.
The complications most often associated with diabetes mellitus include blindness.
Such blindness can result from several causes. Diabetic retinopathy, one of those
causes of blindness, occurs because of the deterioration of the blood vessels in the eye.