OTHER TYPES OF DIABETES
There are less common forms of diabetes in which there is a specific cause
for the beta cell failure or problems with insulin function. Some of these conditions are extremely rare, so I
discuss only the more common ones in the following sections.
Diabetes Due to Gene Mutations
Maturity onset diabetes of the young (MODY) refers to diabetes that occurs
in childhood or adolescence (before age twenty-five) and is inherited in an autosomal dominant fashion; that is,
if you have the condition, half of your children are also likely to have it. About one in one hundred people
with diabetes have MODY. There are six known genetic defects for this kind of diabetes. One of the genetic
defects (called MODY 2) is in the gene that enables the beta cells to sense the body’s glucose level (the
glucose kinase gene) and so regulate insulin release. MODY 2 is usually easily controlled with oral medications
that stimulate insulin release. People with this type of diabetes are usually not
obese.
About one in one hundred people with diabetes have a genetic defect in the
mitochondria (the energy generating machinery of the cell). The genetic defect seems to cause premature aging
of the insulin-secreting beta cells. Since mitochondria are always inherited from the mother and not the father,
this is a maternally inherited form of diabetes. The mitochondrial mutation also leads to nerve damage in the
ear, so that people with this form of diabetes are frequently deaf.
Diabetes Due to Pancreatic Damage
Because the pancreas is responsible for producing insulin, any damage to
the pancreas will cause diabetes. Examples of damage to the pancreas include surgical removal of the pancreas
to fight pancreatic cancer and severe pancreatitis (infl ammation of the pancreas). Cystic fibrosis may lead to
the development of diabetes in early adulthood because of damage to the pancreas and the beta
cells.
Two conditions that cause an excess deposition of iron in the pancreas can
also damage the beta cells and cause diabetes: hemochromatosis and thalassemia major. In the United States, five
in one thousand people carry the genetic defect that causes hemochromatosis. Individuals with this genetic
defect absorb more iron than they should, causing pancreatic damage. If you have thalassemia major, you require
frequent blood transfusions, and this leads to an iron overload that damages the
pancreas.
Diabetes Related to Excessive Hormone
Production
There are a number of hormones that oppose the effects of insulin.
Examples are cortisol, growth hormone, catecholamines, and glucagon. Tumors that make excess amounts of these
hormones can cause diabetes.
Diabetes Induced by Medications
If you have limited beta cell function, using prescription medicines that
either decrease insulin effectiveness and/or further decrease beta cell function can cause diabetes. For
example, steroids such as prednisone and dexamethasone, which are used to treat inflammation, can cause blood
glucose to rise in some people. Niacin, a drug used to lower triglyceride levels and raise HDL cholesterol
levels, reduces insulin effectiveness and can cause an increase in blood glucose.
Drugs that are used to suppress the immune system after an organ
transplant can cause both insulin resistance and reduced beta cell activity, causing
diabetes.
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