What are the different
types of diabetes?
There are two major types
of diabetes, called type 1 and type 2.
Type 2 diabetes was also
referred to as non-insulin dependent diabetes mellitus
(NIDDM), or adult onset diabetes mellitus (AODM). In
type 2 diabetes, patients can still produce insulin,
but do so relatively inadequately for their body’s needs,
particularly in the face of insulin resistance as discussed
above. In many cases this actually means the pancreas
produces larger than normal quantities of insulin. A
major feature of type 2 diabetes is a lack of sensitivity
to insulin by the cells of the body (particularly fat
and muscle cells). In addition to the problems with
an increase in insulin resistance, the release of insulin
by the pancreas may also be defective and suboptimal.
In fact, there is a known steady decline in beta cell
production of insulin in type 2 diabetes that contributes
to worsening glucose control. (This is a major factor
for many patients with type 2 diabetes who ultimately
require insulin therapy.) Finally, the liver in these
patients continues to produce glucose through a process
called gluconeogenesis despite elevated glucose levels.
The control of gluconeogenesis becomes compromised.
While it is said that type 2 diabetes occurs mostly
in individuals over 30 years old and the incidence increases
with age, we are seeing an alarming number patients
with type 2 diabetes who are barely in their teen years.
In fact, for the first time in the history of humans,
type 2 diabetes is now more common than type 1 diabetes
in childhood. Most of these cases are a direct result
of poor eating habits, higher body weight, and lack
of exercise. While there is a strong genetic component
to developing this form of diabetes, there are other
risk factors - the most significant of which is obesity.
There is a direct relationship between the degree of
obesity and the risk of developing type 2 diabetes,
and this holds true in children as well as adults.
Finally, diabetes occurs
much more frequently in women with a prior history of
diabetes that develops during pregnancy (gestational
diabetes - see below). Diabetes can occur temporarily
during pregnancy. Significant hormonal changes during
pregnancy can lead to blood sugar elevation in genetically
predisposed individuals. Blood sugar elevation during
pregnancy is called gestational diabetes. Gestational
diabetes usually resolves once the baby is born. However,
25-50% of women with gestational diabetes will eventually
develop Type 2 diabetes later in life, especially in
those who require insulin during pregnancy and those
who remain overweight after their delivery. Patients
with gestational diabetes are usually asked to undergo
an oral glucose tolerance test about 6 weeks after giving
birth to determine if their diabetes has persisted beyond
the pregnancy, or if any evidence (such as impaired
glucose tolerance) is present that may be a clue to
the patient’s future risk for developing diabetes.
"Secondary" diabetes refers
to elevated blood sugar levels from another medical
condition. Secondary diabetes may develop when the pancreatic
tissue responsible for the production of insulin is
destroyed by disease, such as chronic pancreatitis (inflammation
of the pancreas by toxins like excessive alcohol), trauma,
or surgical removal of the pancreas. Diabetes can also
result from other hormonal disturbances, such as excessive
growth hormone production (acromegaly) and Cushing's
syndrome. In acromegaly, a pituitary gland tumor at
the base of the brain causes excessive production of
growth hormone, leading to hyperglycemia. In Cushing's
syndrome, the adrenal glands produce an excess of cortisol,
which promotes blood sugar elevation.
In addition, certain medications
may worsen diabetes control, or "unmask" latent diabetes.
This is seen most commonly when steroid medications
(such as prednisone) are taken and also with medications
used in the treatment of HIV infection (AIDS).
|
